The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-4698-1 advisory.

    Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly handled memory when sorting RRsets. A     remote attacker could use this issue to cause Dnsmasq to hang, resulting in a denial of service, or     possibly execute arbitrary code. (CVE-2020-25681, CVE-2020-25687)

    Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly handled extracting certain names. A     remote attacker could use this issue to cause Dnsmasq to hang, resulting in a denial of service, or     possibly execute arbitrary code. (CVE-2020-25682, CVE-2020-25683)

    Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly implemented address/port checks. A remote     attacker could use this issue to perform a cache poisoning attack. (CVE-2020-25684)

    Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly implemented query resource name checks. A     remote attacker could use this issue to perform a cache poisoning attack. (CVE-2020-25685)

    Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly handled multiple query requests for the     same resource name. A remote attacker could use this issue to perform a cache poisoning attack.
    (CVE-2020-25686)

    It was discovered that Dnsmasq incorrectly handled memory during DHCP response creation. A remote attacker     could possibly use this issue to cause Dnsmasq to consume resources, leading to a denial of service. This     issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2019-14834)

Tenable has extracted the preceding description block directly from the Ubuntu 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 Fedora 33 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2021-84440e87ba advisory.

  - A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in the way     RRSets are sorted before validating with DNSSEC data. An attacker on the network, who can forge DNS     replies such as that they are accepted as valid, could use this flaw to cause a buffer overflow with     arbitrary data in a heap memory segment, possibly executing code on the machine. The highest threat from     this vulnerability is to data confidentiality and integrity as well as system availability.
    (CVE-2020-25681)

  - A flaw was found in dnsmasq before 2.83. A buffer overflow vulnerability was discovered in the way dnsmasq     extract names from DNS packets before validating them with DNSSEC data. An attacker on the network, who     can create valid DNS replies, could use this flaw to cause an overflow with arbitrary data in a heap-     allocated memory, possibly executing code on the machine. The flaw is in the rfc1035.c:extract_name()     function, which writes data to the memory pointed by name assuming MAXDNAME*2 bytes are available in the     buffer. However, in some code execution paths, it is possible extract_name() gets passed an offset from     the base buffer, thus reducing, in practice, the number of available bytes that can be written in the     buffer. The highest threat from this vulnerability is to data confidentiality and integrity as well as     system availability. (CVE-2020-25682)

  - A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq     when DNSSEC is enabled and before it validates the received DNS entries. A remote attacker, who can create     valid DNS replies, could use this flaw to cause an overflow in a heap-allocated memory. This flaw is     caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code     execute memcpy() with a negative size in get_rdata() and cause a crash in dnsmasq, resulting in a denial     of service. The highest threat from this vulnerability is to system availability. (CVE-2020-25683)

  - A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq     checks in the forward.c:reply_query() if the reply destination address/port is used by the pending     forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query,     substantially reducing the number of attempts an attacker on the network would have to perform to forge a     reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's     attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache     Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful     attack is reduced. The highest threat from this vulnerability is to data integrity. (CVE-2020-25684)

  - A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq     checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a     weak hash of the query name. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1     when it is) this flaw allows an off-path attacker to find several different domains all having the same     hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it     accepted by dnsmasq. This is in contrast with RFC5452, which specifies that the query name is one of the     attributes of a query that must be used to match a reply. This flaw could be abused to perform a DNS Cache     Poisoning attack. If chained with CVE-2020-25684 the attack complexity of a successful attack is reduced.
    The highest threat from this vulnerability is to data integrity. (CVE-2020-25685)

  - A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an     existing pending request for the same name and forwards a new request. By default, a maximum of 150     pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name.
    This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that     it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the     Birthday Attacks section of RFC5452. If chained with CVE-2020-25684, the attack complexity of a     successful attack is reduced. The highest threat from this vulnerability is to data integrity.
    (CVE-2020-25686)

  - A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq     when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote     attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is     caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code     execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial     of service. The highest threat from this vulnerability is to system availability. (CVE-2020-25687)

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

An update of the dnsmasq package has been released.

New dnsmasq packages are available for Slackware 14.0, 14.1, 14.2, and -current to fix security issues.

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

  - A flaw was found in dnsmasq. A heap-based buffer     overflow was discovered in dnsmasq when DNSSEC is     enabled and before it validates the received DNS     entries. This flaw allows a remote attacker, who can     create valid DNS replies, to cause an overflow in a     heap-allocated memory. This flaw is caused by the lack     of length checks in rfc1035.c:extract_name(), which     could be abused to make the code execute memcpy() with     a negative size in sort_rrset() and cause a crash in     dnsmasq, resulting in a denial of service. The highest     threat from this vulnerability is to system     availability.(CVE-2020-25687)

  - A flaw was found in dnsmasq. When receiving a query,     dnsmasq does not check for an existing pending request     for the same name and forwards a new request. By     default, a maximum of 150 pending queries can be sent     to upstream servers, so there can be at most 150     queries for the same name. This flaw allows an off-path     attacker on the network to substantially reduce the     number of attempts that it would have to perform to     forge a reply and have it accepted by dnsmasq. This     issue is mentioned in the 'Birthday Attacks' section of     RFC5452. If chained with CVE-2020-25684, the attack     complexity of a successful attack is reduced. The     highest threat from this vulnerability is to data     integrity.(CVE-2020-25686)

  - A flaw was found in dnsmasq. When getting a reply from     a forwarded query, dnsmasq checks in     forward.c:reply_query(), which is the forwarded query     that matches the reply, by only using a weak hash of     the query name. Due to the weak hash (CRC32 when     dnsmasq is compiled without DNSSEC, SHA-1 when it is)     this flaw allows an off-path attacker to find several     different domains all having the same hash,     substantially reducing the number of attempts they     would have to perform to forge a reply and get it     accepted by dnsmasq. This is in contrast with RFC5452,     which specifies that the query name is one of the     attributes of a query that must be used to match a     reply. This flaw could be abused to perform a DNS Cache     Poisoning attack. If chained with CVE-2020-25684 the     attack complexity of a successful attack is reduced.
    The highest threat from this vulnerability is to data     integrity.(CVE-2020-25685)

  - A flaw was found in dnsmasq. When getting a reply from     a forwarded query, dnsmasq checks in the     forward.c:reply_query() if the reply destination     address/port is used by the pending forwarded queries.
    However, it does not use the address/port to retrieve     the exact forwarded query, substantially reducing the     number of attempts an attacker on the network would     have to perform to forge a reply and get it accepted by     dnsmasq. This issue contrasts with RFC5452, which     specifies a query's attributes that all must be used to     match a reply. This flaw allows an attacker to perform     a DNS Cache Poisoning attack. If chained with     CVE-2020-25685 or CVE-2020-25686, the attack complexity     of a successful attack is reduced. The highest threat     from this vulnerability is to data     integrity.(CVE-2020-25684)

  - A flaw was found in dnsmasq. A heap-based buffer     overflow was discovered in dnsmasq when DNSSEC is     enabled and before it validates the received DNS     entries. A remote attacker, who can create valid DNS     replies, could use this flaw to cause an overflow in a     heap-allocated memory. This flaw is caused by the lack     of length checks in rfc1035.c:extract_name(), which     could be abused to make the code execute memcpy() with     a negative size in get_rdata() and cause a crash in     dnsmasq, resulting in a denial of service. The highest     threat from this vulnerability is to system     availability.(CVE-2020-25683)

  - A flaw was found in dnsmasq. A buffer overflow     vulnerability was discovered in the way dnsmasq extract     names from DNS packets before validating them with     DNSSEC data. An attacker on the network, who can create     valid DNS replies, could use this flaw to cause an     overflow with arbitrary data in a heap-allocated     memory, possibly executing code on the machine. The     flaw is in the rfc1035.c:extract_name() function, which     writes data to the memory pointed by name assuming     MAXDNAME*2 bytes are available in the buffer. However,     in some code execution paths, it is possible     extract_name() gets passed an offset from the base     buffer, thus reducing, in practice, the number of     available bytes that can be written in the buffer. The     highest threat from this vulnerability is to data     confidentiality and integrity as well as system     availability.(CVE-2020-25682)

  - A flaw was found in dnsmasq. A heap-based buffer     overflow was discovered in the way RRSets are sorted     before validating with DNSSEC data. An attacker on the     network, who can forge DNS replies such as that they     are accepted as valid, could use this flaw to cause a     buffer overflow with arbitrary data in a heap memory     segment, possibly executing code on the machine. The     highest threat from this vulnerability is to data     confidentiality and integrity as well as system     availability.(CVE-2020-25681)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Redhat Enterprise Linux 7 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2021:0395 advisory.

    The redhat-virtualization-host packages provide the Red Hat Virtualization Host. These packages include     redhat-release-virtualization-host. Red Hat Virtualization Hosts (RHVH) are installed using a special     build of Red Hat Enterprise Linux with only the packages required to host virtual machines. RHVH features     a Cockpit user interface for monitoring the host's resources and performing administrative tasks.

    Security Fix(es):

    * sudo: Heap buffer overflow in argument parsing (CVE-2021-3156)

    * dnsmasq: loose address/port check in reply_query() makes forging replies easier for an off-path attacker     (CVE-2020-25684)

    * dnsmasq: loose query name check in reply_query() makes forging replies easier for an off-path attacker     (CVE-2020-25685)

    * dnsmasq: multiple queries forwarded for the same name makes forging replies easier for an off-path     attacker (CVE-2020-25686)

    For more details about the security issue(s), including the impact, a CVSS score, and other related     information, refer to the CVE page(s) listed in the References section.

    Bug Fix(es):

    * When performing an upgrade of the Red Hat Virtualization Host using the command `yum update`, the yum     repository for RHV 4.3 EUS is unreachable

    As a workaround, run the following command:
    `# yum update --releasever=7Server` (BZ#1899378)

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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
145078	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Dnsmasq vulnerabilities (USN-4698-1)	Nessus	Ubuntu Local Security Checks	1/19/2021	9/3/2025	high
145241	Fedora 33 : dnsmasq (2021-84440e87ba)	Nessus	Fedora Local Security Checks	1/21/2021	12/5/2022	high
145421	Photon OS 2.0: Dnsmasq PHSA-2021-2.0-0312	Nessus	PhotonOS Local Security Checks	1/26/2021	7/22/2024	high
146369	Slackware 14.0 / 14.1 / 14.2 / current : dnsmasq (SSA:2021-040-01)	Nessus	Slackware Local Security Checks	2/10/2021	1/22/2024	high
148581	EulerOS Virtualization 2.9.0 : dnsmasq (EulerOS-SA-2021-1758)	Nessus	Huawei Local Security Checks	4/15/2021	1/4/2024	high
148613	EulerOS Virtualization 2.9.1 : dnsmasq (EulerOS-SA-2021-1733)	Nessus	Huawei Local Security Checks	4/15/2021	1/4/2024	high
146093	RHEL 7 : RHV-H security, update (redhat-virtualization-host) 4.3.13 (Important) (RHSA-2021:0395)	Nessus	Red Hat Local Security Checks	2/3/2021	11/7/2024	high

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