The version of unbound installed on the remote host is prior to 1.17.0-2. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2UNBOUND-1.17-2026-008 advisory.

    NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator     that enables denial of service and possible remote code execution as a result of deep copying a data     structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by     controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend     validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-     copies response messages to preserve them across memory region teardown. A struct-assignment bug     overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the     resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary     code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep     copying the data structure. (CVE-2026-33278)

    NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain     names' family of attacks that could extend the ghost domain window by up to one cached TTL configured     value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be     able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached     expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost     domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-     referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound     implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension     of TTLs for (parent) NS records regardless of their trust. (CVE-2026-40622)

    NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack     related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS     options can hold Unbound threads hostage while they are parsing and creating internal data structures for     the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1     contains a patch with a fix to limit acceptable incoming EDNS options (100). (CVE-2026-41292)

    NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could     defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age     of slow running queries and not allow the jostle logic to see them as aged and potential targets for     replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain     name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and     degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit,     the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to     resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need     resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the     original one that started the resolution effort. Cache and local data response performance remains     unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1     contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow     the jostle logic to work as intended. (CVE-2026-42534)

    NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the DNSSEC validator where     the code path to consult the negative cache for DS records does not take into account the limit on NSEC3     hash calculations introduced in 1.19.1. This leads to degradation of service during the attack. An     adversary that controls a DNSSEC signed zone can exploit this by signing NSEC3 records with acceptably     high iterations for child delegations and querying a vulnerable Unbound. Unbound will keep performing the     allowed hash calculations on the NSEC3 records and will not limit the work by the mitigation introduced in     1.19.1. As a side effect, a global lock for the negative cache will be held for the duration of the     hashing, blocking other threads that need to consult the negative cache. Coordinated attacks could raise     the vulnerability to denial of service. Unbound 1.25.1 contains a patch with a fix to bound the vulnerable     code path with the existing limit for NSEC3 hash calculations. (CVE-2026-42923)

    NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap     overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply     packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for     the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by     attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the     size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the     available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data     and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-duplicate the EDNS options and a     fix to prevent truncation of the EDNS field size calculation. (CVE-2026-42944)

    NLnet Labs Unbound up to and including version 1.25.0 has a denial of service vulnerability in the DNSSEC     validator that can lead to a crash given malicious upstream replies. When Unbound constructs chase-reply     messages for validation, the code uses the wrong counter to calculate write offsets for ADDITIONAL section     rrsets. DNAME duplication could increase the ANSWER section count and authority filtering could decrease     the AUTHORITY section count and create an uninitialized array slot. Combining these two, the validator     later dereferences this uninitialized pointer, causing an immediate process crash. An adversary     controlling a DNSSEC-signed domain can trigger this bug with a single query by configuring a DNAME chain     with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue     records. Unbound 1.25.1 contains a patch with a fix to use the proper counters to calculate the write     offsets. (CVE-2026-42959)

    NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records     for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be     used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply     (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor     can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by     address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or     fragmentation attacks. Unbound would then accept the relative address records in the additional section     and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the     delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the     additional section if they are not explicitly relevant only to authority NS records, mitigating the     possible poison effect. This is a complement fix to CVE-2025-11411. (CVE-2026-42960)

    NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very     large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very     large RRsets with records that don't share a suffix above the root can cause Unbound to spend a     considerable time applying name compression to downstream replies. This can lead to degraded performance     and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability     by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before     Unbound replies to the query it will try to apply name compression which was an unbounded operation that     could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for     this but it didn't account for the case where records would not share any suffix above the root. That     causes Unbound to go in a different code path because of the compression tree lookup failure and     eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch     with a fix that increments the compression counter regardless of the compression tree lookup. This is a     complement fix to CVE-2024-8508. (CVE-2026-44390)

    NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability     that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-     nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the     vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with     'rpz-nsip'/'rpz-nsdname' triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the     vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read     that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free     objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with     a fix to the locking code. (CVE-2026-44608)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

According to the versions of the unbound packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

    NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records     for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be     used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply     (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor     can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by     address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or     fragmentation attacks. Unbound would then accept the relative address records in the additional section     and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the     delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the     additional section if they are not explicitly relevant only to authority NS records, mitigating the     possible poison effect. This is a complement fix to CVE-2025-11411.(CVE-2026-42960)

    NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain     names' family of attacks that could extend the ghost domain window by up to one cached TTL configured     value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be     able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached     expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost     domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-     referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound     implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension     of TTLs for (parent) NS records regardless of their trust.(CVE-2026-40622)

    NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack     related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS     options can hold Unbound threads hostage while they are parsing and creating internal data structures for     the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1     contains a patch with a fix to limit acceptable incoming EDNS options (100).(CVE-2026-41292)

    NLnet Labs Unbound up to and including version 1.25.0 has a denial of service vulnerability in the DNSSEC     validator that can lead to a crash given malicious upstream replies. When Unbound constructs chase-reply     messages for validation, the code uses the wrong counter to calculate write offsets for ADDITIONAL section     rrsets. DNAME duplication could increase the ANSWER section count and authority filtering could decrease     the AUTHORITY section count and create an uninitialized array slot. Combining these two, the validator     later dereferences this uninitialized pointer, causing an immediate process crash. An adversary     controlling a DNSSEC-signed domain can trigger this bug with a single query by configuring a DNAME chain     with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue     records. Unbound 1.25.1 contains a patch with a fix to use the proper counters to calculate the write     offsets.(CVE-2026-42959)

    NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator     that enables denial of service and possible remote code execution as a result of deep copying a data     structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by     controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend     validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-     copies response messages to preserve them across memory region teardown. A struct-assignment bug     overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the     resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary     code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep     copying the data structure.(CVE-2026-33278)

Tenable has extracted the preceding description block directly from the EulerOS Virtualization unbound security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of F5 Networks BIG-IP installed on the remote host is prior to 17.1.3.5 / 17.5.1.9 / 21.1.0.2. It is, therefore, affected by a vulnerability as referenced in the K000163139 advisory.

    NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator     that enables denial of service and possible remote code execution as a result of deep copying a data     structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by     controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend     validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-     copies response messages to preserve them across memory region teardown. A struct-assignment bug     overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the     resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary     code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep     copying the data structure.(CVE-2026-33278)

Tenable has extracted the preceding description block directly from the F5 Networks BIG-IP security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

According to the versions of the unbound packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

    DISPUTE NOTE: this issue does not pose a security risk as it (according to analysis by the original     software developer, NLnet Labs) falls within the expected functionality and security controls of the     application. Red Hat has made a claim that there is a security risk within Red Hat products. NLnet Labs     has no further information about the claim, and suggests that affected Red Hat customers refer to     available Red Hat documentation or support channels. ORIGINAL DESCRIPTION: A heap-buffer-overflow flaw was     found in the cfg_mark_ports function within Unbound's config_file.c, which can lead to memory corruption.
    This issue could allow an attacker with local access to provide specially crafted input, potentially     causing the application to crash or allowing arbitrary code execution. This could result in a denial of     service or unauthorized actions on the system.(CVE-2024-43168)

    NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with     very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very     large RRsets can cause Unbound to spend a considerable time applying name compression to downstream     replies. This can lead to degraded performance and eventually denial of service in well orchestrated     attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially     crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will     try to apply name compression which was an unbounded operation that could lock the CPU until the whole     packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression     calculations it is willing to do per packet. Packets that need more compression will result in semi-     compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long.
    This change should not affect normal DNS traffic.(CVE-2024-8508)

    The DNS protocol in RFC 1035 and updates allows remote attackers to cause a denial of service (resource     consumption) by arranging for DNS queries to be accumulated for seconds, such that responses are later     sent in a pulsing burst (which can be considered traffic amplification in some cases), aka the 'DNSBomb'     issue.(CVE-2024-33655)

    A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching     resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS     support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream     name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-     always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to     accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox     attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous     replies.(CVE-2025-5994)

    NLnet Labs Unbound up to and including version 1.24.1 is vulnerable to possible domain hijack attacks.
    Promiscuous NS RRSets that complement positive DNS replies in the authority section can be used to trick     resolvers to update their delegation information for the zone. Usually these RRSets are used to update the     resolver's knowledge of the zone's name servers. A malicious actor can exploit the possible poisonous     effect by injecting NS RRSets (and possibly their respective address records) in a reply. This could be     done for example by trying to spoof a packet or fragmentation attacks. Unbound would then proceed to     update the NS RRSet data it already has since the new data has enough trust for it, i.e., in-zone data for     the delegation point. Unbound 1.24.1 includes a fix that scrubs unsolicited NS RRSets (and their     respective address records) from replies mitigating the possible poison effect. Unbound 1.24.2 includes an     additional fix that scrubs unsolicited NS RRSets (and their respective address records) from YXDOMAIN and     non-referral nodata replies, further mitigating the possible poison effect.(CVE-2025-11411)

    NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator     that enables denial of service and possible remote code execution as a result of deep copying a data     structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by     controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend     validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-     copies response messages to preserve them across memory region teardown. A struct-assignment bug     overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the     resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary     code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep     copying the data structure.(CVE-2026-33278)

    NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records     for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be     used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply     (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor     can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by     address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or     fragmentation attacks. Unbound would then accept the relative address records in the additional section     and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the     delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the     additional section if they are not explicitly relevant only to authority NS records, mitigating the     possible poison effect. This is a complement fix to CVE-2025-11411.(CVE-2026-42960)

    NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could     defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age     of slow running queries and not allow the jostle logic to see them as aged and potential targets for     replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain     name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and     degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit,     the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to     resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need     resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the     original one that started the resolution effort. Cache and local data response performance remains     unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1     contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow     the jostle logic to work as intended.(CVE-2026-42534)

    NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the DNSSEC validator where     the code path to consult the negative cache for DS records does not take into account the limit on NSEC3     hash calculations introduced in 1.19.1. This leads to degradation of service during the attack. An     adversary that controls a DNSSEC signed zone can exploit this by signing NSEC3 records with acceptably     high iterations for child delegations and querying a vulnerable Unbound. Unbound will keep performing the     allowed hash calculations on the NSEC3 records and will not limit the work by the mitigation introduced in     1.19.1. As a side effect, a global lock for the negative cache will be held for the duration of the     hashing, blocking other threads that need to consult the negative cache. Coordinated attacks could raise     the vulnerability to denial of service. Unbound 1.25.1 contains a patch with a fix to bound the vulnerable     code path with the existing limit for NSEC3 hash calculations.(CVE-2026-42923)

    NLnet Labs Unbound 1.6.2 up to and including version 1.25.0 has a denial of service vulnerability when     compiled with DNSCrypt support ('--enable-dnscrypt'). A bad DNSCrypt query could underflow Unbound's     DNSCrypt packet reading procedure that may lead to heap overflow. A malicious actor can exploit the     vulnerability with a single bad DNSCrypt query that its decrypted plaintext consists entirely of '0x00'     bytes and does not contain the expected '0x80' marker. Unbound would then start reading more bytes than     necessary until it finds a non-'0x00' byte. Based on the underlying memory allocator and the memory     layout, it could lead to heap overflow while reading followed by a crash. Likelihood of a crash is low,     since it relies heavily on the underlying memory allocator and the memory layout. If the heap overflow     does not happen, Unbound's later packet checks will deny the packet. Unbound 1.25.1 contains a patch with     a fix to bound reading in the given buffer space.(CVE-2026-32792)

    NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack     related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS     options can hold Unbound threads hostage while they are parsing and creating internal data structures for     the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1     contains a patch with a fix to limit acceptable incoming EDNS options (100).(CVE-2026-41292)

    NLnet Labs Unbound up to and including version 1.25.0 has a denial of service vulnerability in the DNSSEC     validator that can lead to a crash given malicious upstream replies. When Unbound constructs chase-reply     messages for validation, the code uses the wrong counter to calculate write offsets for ADDITIONAL section     rrsets. DNAME duplication could increase the ANSWER section count and authority filtering could decrease     the AUTHORITY section count and create an uninitialized array slot. Combining these two, the validator     later dereferences this uninitialized pointer, causing an immediate process crash. An adversary     controlling a DNSSEC-signed domain can trigger this bug with a single query by configuring a DNAME chain     with unsigned CNAMEs and a response containing unsigned AUTHORITY records alongside signed ADDITIONAL glue     records. Unbound 1.25.1 contains a patch with a fix to use the proper counters to calculate the write     offsets.(CVE-2026-42959)

    NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very     large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very     large RRsets with records that don't share a suffix above the root can cause Unbound to spend a     considerable time applying name compression to downstream replies. This can lead to degraded performance     and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability     by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before     Unbound replies to the query it will try to apply name compression which was an unbounded operation that     could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for     this but it didn't account for the case where records would not share any suffix above the root. That     causes Unbound to go in a different code path because of the compression tree lookup failure and     eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch     with a fix that increments the compression counter regardless of the compression tree lookup. This is a     complement fix to CVE-2024-8508.(CVE-2026-44390)

    NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain     names' family of attacks that could extend the ghost domain window by up to one cached TTL configured     value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be     able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached     expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost     domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-     referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound     implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension     of TTLs for (parent) NS records regardless of their trust.(CVE-2026-40622)

Tenable has extracted the preceding description block directly from the EulerOS Virtualization unbound security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote NewStart CGSL host, running version MAIN 7.02, has unbound packages installed that are affected by multiple vulnerabilities:

  - NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records     for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be     used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply     (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor     can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by     address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or     fragmentation attacks. Unbound would then accept the relative address records in the additional section     and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the     delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the     additional section if they are not explicitly relevant only to authority NS records, mitigating the     possible poison effect. This is a complement fix to CVE-2025-11411. (CVE-2026-42960)

  - NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator     that enables denial of service and possible remote code execution as a result of deep copying a data     structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by     controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend     validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-     copies response messages to preserve them across memory region teardown. A struct-assignment bug     overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the     resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary     code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep     copying the data structure. (CVE-2026-33278)

  - DISPUTE NOTE: this issue does not pose a security risk as it (according to analysis by the original     software developer, NLnet Labs) falls within the expected functionality and security controls of the     application. Red Hat has made a claim that there is a security risk within Red Hat products. NLnet Labs     has no further information about the claim, and suggests that affected Red Hat customers refer to     available Red Hat documentation or support channels. ORIGINAL DESCRIPTION: A NULL pointer dereference flaw     was found in the ub_ctx_set_fwd function in Unbound. This issue could allow an attacker who can invoke     specific sequences of API calls to cause a segmentation fault. When certain API functions such as     ub_ctx_set_fwd and ub_ctx_resolvconf are called in a particular order, the program attempts to read from a     NULL pointer, leading to a crash. This issue can result in a denial of service by causing the application     to terminate unexpectedly. (CVE-2024-43167)

  - DISPUTE NOTE: this issue does not pose a security risk as it (according to analysis by the original     software developer, NLnet Labs) falls within the expected functionality and security controls of the     application. Red Hat has made a claim that there is a security risk within Red Hat products. NLnet Labs     has no further information about the claim, and suggests that affected Red Hat customers refer to     available Red Hat documentation or support channels. ORIGINAL DESCRIPTION: A heap-buffer-overflow flaw was     found in the cfg_mark_ports function within Unbound's config_file.c, which can lead to memory corruption.
    This issue could allow an attacker with local access to provide specially crafted input, potentially     causing the application to crash or allowing arbitrary code execution. This could result in a denial of     service or unauthorized actions on the system. (CVE-2024-43168)

  - NLnet Labs Unbound up to and including version 1.24.1 is vulnerable to possible domain hijack attacks.
    Promiscuous NS RRSets that complement positive DNS replies in the authority section can be used to trick     resolvers to update their delegation information for the zone. Usually these RRSets are used to update the     resolver's knowledge of the zone's name servers. A malicious actor can exploit the possible poisonous     effect by injecting NS RRSets (and possibly their respective address records) in a reply. This could be     done for example by trying to spoof a packet or fragmentation attacks. Unbound would then proceed to     update the NS RRSet data it already has since the new data has enough trust for it, i.e., in-zone data for     the delegation point. Unbound 1.24.1 includes a fix that scrubs unsolicited NS RRSets (and their     respective address records) from replies mitigating the possible poison effect. Unbound 1.24.2 includes an     additional fix that scrubs unsolicited NS RRSets (and their respective address records) from YXDOMAIN and     non-referral nodata replies, further mitigating the possible poison effect. (CVE-2025-11411)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Published	Updated	Severity
328496	Amazon Linux 2 : unbound, --advisory ALAS2UNBOUND-1.17-2026-008 (ALASUNBOUND-1.17-2026-008)	Nessus	Amazon Linux Local Security Checks	7/20/2026	8/31/2026	critical
328573	EulerOS Virtualization 2.12.0 : unbound (EulerOS-SA-2026-2809)	Nessus	Huawei Local Security Checks	7/21/2026	8/31/2026	critical
341737	F5 Networks BIG-IP : NLnet Labs Unbound vulnerability (K000163139)	Nessus	F5 Networks Local Security Checks	8/31/2026	9/11/2026	critical
347235	EulerOS Virtualization 2.11.1 : unbound (EulerOS-SA-2026-3478)	Nessus	Huawei Local Security Checks	9/18/2026	9/18/2026	critical
343577	NewStart CGSL MAIN 7.02 : unbound Multiple Vulnerabilities (NS-SA-2026-0095)	Nessus	NewStart CGSL Local Security Checks	9/8/2026	9/8/2026	critical

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