The version of OpenSSL installed on the remote host is prior to 3.5.6. It is, therefore, affected by multiple vulnerabilities as referenced in the 3.5.6 advisory.

  - Issue summary: An OpenSSL TLS 1.3 server may fail to negotiate the expected preferred key exchange group     when its key exchange group configuration includes the default by using the 'DEFAULT' keyword. Impact     summary: A less preferred key exchange may be used even when a more preferred group is supported by both     client and server, if the group was not included among the client's initial predicated keyshares. This     will sometimes be the case with the new hybrid post-quantum groups, if the client chooses to defer their     use until specifically requested by the server. If an OpenSSL TLS 1.3 server's configuration uses the     'DEFAULT' keyword to interpolate the built-in default group list into its own configuration, perhaps     adding or removing specific elements, then an implementation defect causes the 'DEFAULT' list to lose its     'tuple' structure, and all server-supported groups were treated as a single sufficiently secure 'tuple',     with the server not sending a Hello Retry Request (HRR) even when a group in a more preferred tuple was     mutually supported. As a result, the client and server might fail to negotiate a mutually supported post-     quantum key agreement group, such as 'X25519MLKEM768', if the client's configuration results in only     'classical' groups (such as 'X25519' being the only ones in the client's initial keyshare prediction).
    OpenSSL 3.5 and later support a new syntax for selecting the most preferred TLS 1.3 key agreement group on     TLS servers. The old syntax had a single 'flat' list of groups, and treated all the supported groups as     sufficiently secure. If any of the keyshares predicted by the client were supported by the server the most     preferred among these was selected, even if other groups supported by the client, but not included in the     list of predicted keyshares would have been more preferred, if included. The new syntax partitions the     groups into distinct 'tuples' of roughly equivalent security. Within each tuple the most preferred group     included among the client's predicted keyshares is chosen, but if the client supports a group from a more     preferred tuple, but did not predict any corresponding keyshares, the server will ask the client to retry     the ClientHello (by issuing a Hello Retry Request or HRR) with the most preferred mutually supported     group. The above works as expected when the server's configuration uses the built-in default group list,     or explicitly defines its own list by directly defining the various desired groups and group 'tuples'. No     OpenSSL FIPS modules are affected by this issue, the code in question lies outside the FIPS boundary.
    OpenSSL 3.6 and 3.5 are vulnerable to this issue. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2 once     it is released. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6 once it is released. OpenSSL 3.4, 3.3,     3.0, 1.0.2 and 1.1.1 are not affected by this issue. (CVE-2026-2673)

  - Issue summary: Applications using RSASVE key encapsulation to establish a secret encryption key can send     contents of an uninitialized memory buffer to a malicious peer.  Impact summary: The uninitialized buffer     might contain sensitive data from the previous execution of the application process which leads to     sensitive data leakage to an attacker.  RSA_public_encrypt() returns the number of bytes written on     success and -1 on error. The affected code tests only whether the return value is non-zero. As a result,     if RSA encryption fails, encapsulation can still return success to the caller, set the output lengths, and     leave the caller to use the contents of the ciphertext buffer as if a valid KEM ciphertext had been     produced.  If applications use EVP_PKEY_encapsulate() with RSA/RSASVE on an attacker-supplied invalid RSA     public key without first validating that key, then this may cause stale or uninitialized contents of the     caller-provided ciphertext buffer to be disclosed to the attacker in place of the KEM ciphertext.  As a     workaround calling EVP_PKEY_public_check() or EVP_PKEY_public_check_quick() before EVP_PKEY_encapsulate()     will mitigate the issue.  The FIPS modules in 3.6, 3.5, 3.4, 3.3, 3.1 and 3.0 are affected by this issue.
    Fixed in OpenSSL 3.0.20 (Affected since 3.0.0). (CVE-2026-31790)

  - Issue summary: Converting an excessively large OCTET STRING value to a hexadecimal string leads to a heap     buffer overflow on 32 bit platforms.  Impact summary: A heap buffer overflow may lead to a crash or     possibly an attacker controlled code execution or other undefined behavior.  If an attacker can supply a     crafted X.509 certificate with an excessively large OCTET STRING value in extensions such as the Subject     Key Identifier (SKID) or Authority Key Identifier (AKID) which are being converted to hex, the size of the     buffer needed for the result is calculated as multiplication of the input length by 3. On 32 bit     platforms, this multiplication may overflow resulting in the allocation of a smaller buffer and a heap     buffer overflow.  Applications and services that print or log contents of untrusted X.509 certificates are     vulnerable to this issue. As the certificates would have to have sizes of over 1 Gigabyte, printing or     logging such certificates is a fairly unlikely operation and only 32 bit platforms are affected, this     issue was assigned Low severity.  The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this     issue, as the affected code is outside the OpenSSL FIPS module boundary. Fixed in OpenSSL 3.0.20 (Affected     since 3.0.0). (CVE-2026-31789)

  - Issue summary: During processing of a crafted CMS EnvelopedData message with KeyTransportRecipientInfo a     NULL pointer dereference can happen.  Impact summary: Applications that process attacker-controlled CMS     data may crash before authentication or cryptographic operations occur resulting in Denial of Service.
    When a CMS EnvelopedData message that uses KeyTransportRecipientInfo with RSA-OAEP encryption is     processed, the optional parameters field of RSA-OAEP SourceFunc algorithm identifier is examined without     checking for its presence. This results in a NULL pointer dereference if the field is missing.
    Applications and services that call CMS_decrypt() on untrusted input (e.g., S/MIME processing or CMS-based     protocols) are vulnerable.  The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue,     as the affected code is outside the OpenSSL FIPS module boundary. Fixed in OpenSSL 1.1.1zg (Affected since     1.1.1). (CVE-2026-28390)

  - Issue summary: During processing of a crafted CMS EnvelopedData message with KeyAgreeRecipientInfo a NULL     pointer dereference can happen.  Impact summary: Applications that process attacker-controlled CMS data     may crash before authentication or cryptographic operations occur resulting in Denial of Service.  When a     CMS EnvelopedData message that uses KeyAgreeRecipientInfo is processed, the optional parameters field of     KeyEncryptionAlgorithmIdentifier is examined without checking for its presence. This results in a NULL     pointer dereference if the field is missing.  Applications and services that call CMS_decrypt() on     untrusted input (e.g., S/MIME processing or CMS-based protocols) are vulnerable.  The FIPS modules in 3.6,     3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS     module boundary. Fixed in OpenSSL 1.1.1zg (Affected since 1.1.1). (CVE-2026-28389)

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 OpenSSL installed on the remote host is prior to 3.6.2. It is, therefore, affected by multiple vulnerabilities as referenced in the 3.6.2 advisory.

  - Issue summary: An OpenSSL TLS 1.3 server may fail to negotiate the expected preferred key exchange group     when its key exchange group configuration includes the default by using the 'DEFAULT' keyword. Impact     summary: A less preferred key exchange may be used even when a more preferred group is supported by both     client and server, if the group was not included among the client's initial predicated keyshares. This     will sometimes be the case with the new hybrid post-quantum groups, if the client chooses to defer their     use until specifically requested by the server. If an OpenSSL TLS 1.3 server's configuration uses the     'DEFAULT' keyword to interpolate the built-in default group list into its own configuration, perhaps     adding or removing specific elements, then an implementation defect causes the 'DEFAULT' list to lose its     'tuple' structure, and all server-supported groups were treated as a single sufficiently secure 'tuple',     with the server not sending a Hello Retry Request (HRR) even when a group in a more preferred tuple was     mutually supported. As a result, the client and server might fail to negotiate a mutually supported post-     quantum key agreement group, such as 'X25519MLKEM768', if the client's configuration results in only     'classical' groups (such as 'X25519' being the only ones in the client's initial keyshare prediction).
    OpenSSL 3.5 and later support a new syntax for selecting the most preferred TLS 1.3 key agreement group on     TLS servers. The old syntax had a single 'flat' list of groups, and treated all the supported groups as     sufficiently secure. If any of the keyshares predicted by the client were supported by the server the most     preferred among these was selected, even if other groups supported by the client, but not included in the     list of predicted keyshares would have been more preferred, if included. The new syntax partitions the     groups into distinct 'tuples' of roughly equivalent security. Within each tuple the most preferred group     included among the client's predicted keyshares is chosen, but if the client supports a group from a more     preferred tuple, but did not predict any corresponding keyshares, the server will ask the client to retry     the ClientHello (by issuing a Hello Retry Request or HRR) with the most preferred mutually supported     group. The above works as expected when the server's configuration uses the built-in default group list,     or explicitly defines its own list by directly defining the various desired groups and group 'tuples'. No     OpenSSL FIPS modules are affected by this issue, the code in question lies outside the FIPS boundary.
    OpenSSL 3.6 and 3.5 are vulnerable to this issue. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2 once     it is released. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6 once it is released. OpenSSL 3.4, 3.3,     3.0, 1.0.2 and 1.1.1 are not affected by this issue. (CVE-2026-2673)

  - Debian Linux - openssl - None  Red Hat Enterprise Linux - openssl: openssl: Information Disclosure from     Uninitialized Memory via Invalid RSA Public Key (CVE-2026-31790)

  - Debian Linux - openssl - None (CVE-2026-28389, CVE-2026-28390, CVE-2026-31789)

  - Issue summary: When a delta CRL that contains a Delta CRL Indicator extension is processed a NULL pointer     dereference might happen if the required CRL Number extension is missing.  Impact summary: A NULL pointer     dereference can trigger a crash which leads to a Denial of Service for an application.  When CRL     processing and delta CRL processing is enabled during X.509 certificate verification, the delta CRL     processing does not check whether the CRL Number extension is NULL before dereferencing it. When a     malformed delta CRL file is being processed, this parameter can be NULL, causing a NULL pointer     dereference.  Exploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in the     verification context, the certificate being verified to contain a freshestCRL extension or the base CRL to     have the EXFLAG_FRESHEST flag set, and an attacker to provide a malformed CRL to an application that     processes it.  The vulnerability is limited to Denial of Service and cannot be escalated to achieve code     execution or memory disclosure. For that reason the issue was assessed as Low severity according to our     Security Policy.  The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the     affected code is outside the OpenSSL FIPS module boundary. Fixed in OpenSSL 3.6.2 (Affected since 3.6.0).
    (CVE-2026-28388)

  - Issue summary: An uncommon configuration of clients performing DANE TLSA-based server authentication, when     paired with uncommon server DANE TLSA records, may result in a use-after-free and/or double-free on the     client side.  Impact summary: A use after free can have a range of potential consequences such as the     corruption of valid data, crashes or execution of arbitrary code.  However, the issue only affects clients     that make use of TLSA records with both the PKIX-TA(0/PKIX-EE(1) certificate usages and the DANE-TA(2)     certificate usage.  By far the most common deployment of DANE is in SMTP MTAs for which RFC7672 recommends     that clients treat as 'unusable' any TLSA records that have the PKIX certificate usages.  These SMTP (or     other similar) clients are not vulnerable to this issue.  Conversely, any clients that support only the     PKIX usages, and ignore the DANE-TA(2) usage are also not vulnerable.  The client would also need to be     communicating with a server that publishes a TLSA RRset with both types of TLSA records.  No FIPS modules     are affected by this issue, the problem code is outside the FIPS module boundary. Fixed in OpenSSL 3.6.2     (Affected since 3.6.0). (CVE-2026-28387)

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 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-d3e275d525 advisory.

    Backport security patches from OpenSSL 3.5.6


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

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

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the ee1e6a24-1eeb-11f1-81da-8447094a420f advisory.

    The OpenSSL project reports:
    TLS 1.3 server may choose unexpected key agreement group (Low)     An OpenSSL TLS 1.3 server may fail to negotiate the expected                 preferred key exchange group when its key exchange group configuration includes                 the default by using the DEFAULT keyword.

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

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

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Issue summary: An OpenSSL TLS 1.3 server may fail to negotiate the expected preferred key exchange group     when its key exchange group configuration includes the default by using the 'DEFAULT' keyword. Impact     summary: A less preferred key exchange may be used even when a more preferred group is supported by both     client and server, if the group was not included among the client's initial predicated keyshares. This     will sometimes be the case with the new hybrid post-quantum groups, if the client chooses to defer their     use until specifically requested by the server. If an OpenSSL TLS 1.3 server's configuration uses the     'DEFAULT' keyword to interpolate the built-in default group list into its own configuration, perhaps     adding or removing specific elements, then an implementation defect causes the 'DEFAULT' list to lose its     'tuple' structure, and all server-supported groups were treated as a single sufficiently secure 'tuple',     with the server not sending a Hello Retry Request (HRR) even when a group in a more preferred tuple was     mutually supported. As a result, the client and server might fail to negotiate a mutually supported post-     quantum key agreement group, such as 'X25519MLKEM768', if the client's configuration results in only     'classical' groups (such as 'X25519' being the only ones in the client's initial keyshare prediction).
    OpenSSL 3.5 and later support a new syntax for selecting the most preferred TLS 1.3 key agreement group on     TLS servers. The old syntax had a single 'flat' list of groups, and treated all the supported groups as     sufficiently secure. If any of the keyshares predicted by the client were supported by the server the most     preferred among these was selected, even if other groups supported by the client, but not included in the     list of predicted keyshares would have been more preferred, if included. The new syntax partitions the     groups into distinct 'tuples' of roughly equivalent security. Within each tuple the most preferred group     included among the client's predicted keyshares is chosen, but if the client supports a group from a more     preferred tuple, but did not predict any corresponding keyshares, the server will ask the client to retry     the ClientHello (by issuing a Hello Retry Request or HRR) with the most preferred mutually supported     group. The above works as expected when the server's configuration uses the built-in default group list,     or explicitly defines its own list by directly defining the various desired groups and group 'tuples'. No     OpenSSL FIPS modules are affected by this issue, the code in question lies outside the FIPS boundary.
    OpenSSL 3.6 and 3.5 are vulnerable to this issue. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2 once     it is released. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6 once it is released. OpenSSL 3.4, 3.3,     3.0, 1.0.2 and 1.1.1 are not affected by this issue. (CVE-2026-2673)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8155-1 advisory.

    Viktor Dukhovni discovered that OpenSSL incorrectly negotiated the expected preferred key exchange group     when used as a TLS 1.3 server. This could result in a less preferred key exchange being used, contrary to     expectations. This issue only affected Ubuntu 25.10. (CVE-2026-2673)

    Igor Morgenstern discovered that OpenSSL incorrectly handled certain memory operations when used as a DANE     client. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of     service, or possibly execute arbitrary code. (CVE-2026-28387)

    Igor Morgenstern discovered that OpenSSL incorrectly handled certain memory operations when processing a     delta CRL. A remote attacker could possibly use this issue to cause OpenSSL to crash, resulting in a     denial of service. (CVE-2026-28388)

    Nathan Sportsman, Daniel Rhea, and Jaeho Nam discovered that OpenSSL incorrectly handled certain memory     operations when processing a crafted CMS EnvelopedData message with KeyAgreeRecipientInfo. A remote     attacker could possibly use this issue to cause OpenSSL to crash, resulting in a denial of service.
    (CVE-2026-28389)

    Muhammad Daffa, Joshua Rogers, and Chanho Kim discovered that OpenSSL incorrectly handled processing of a     crafted CMS EnvelopedData message with KeyTransportRecipientInfo. A remote attacker could possibly use     this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2026-28390)

    Quoc Tran discovered that OpenSSL incorrectly handled hexadecimal conversion on 32-bit platforms. A remote     attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service, or possibly     execute arbitrary code. (CVE-2026-31789)

    Simo Sorce discovered that OpenSSL incorrectly handled failures in RSA KEM RSASVE Encapsulation. A remote     attacker could possibly use this issue to obtain sensitive information. (CVE-2026-31790)

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.

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1522 advisory.

    Issue summary: An OpenSSL TLS 1.3 server may fail to negotiate the expected preferred key exchange group     when its key exchange group configuration includes the default by using the 'DEFAULT' keyword. Impact     summary: A less preferred key exchange may be used even when a more preferred group is supported by both     client and server, if the group was not included among the client's initial predicated keyshares. This     will sometimes be the case with the new hybrid post-quantum groups, if the client chooses to defer their     use until specifically requested by the server. If an OpenSSL TLS 1.3 server's configuration uses the     'DEFAULT' keyword to interpolate the built-in default group list into its own configuration, perhaps     adding or removing specific elements, then an implementation defect causes the 'DEFAULT' list to lose its     'tuple' structure, and all server-supported groups were treated as a single sufficiently secure 'tuple',     with the server not sending a Hello Retry Request (HRR) even when a group in a more preferred tuple was     mutually supported. As a result, the client and server might fail to negotiate a mutually supported post-     quantum key agreement group, such as 'X25519MLKEM768', if the client's configuration results in only     'classical' groups (such as 'X25519' being the only ones in the client's initial keyshare prediction).
    OpenSSL 3.5 and later support a new syntax for selecting the most preferred TLS 1.3 key agreement group on     TLS servers. The old syntax had a single 'flat' list of groups, and treated all the supported groups as     sufficiently secure. If any of the keyshares predicted by the client were supported by the server the most     preferred among these was selected, even if other groups supported by the client, but not included in the     list of predicted keyshares would have been more preferred, if included. The new syntax partitions the     groups into distinct 'tuples' of roughly equivalent security. Within each tuple the most preferred group     included among the client's predicted keyshares is chosen, but if the client supports a group from a more     preferred tuple, but did not predict any corresponding keyshares, the server will ask the client to retry     the ClientHello (by issuing a Hello Retry Request or HRR) with the most preferred mutually supported     group. The above works as expected when the server's configuration uses the built-in default group list,     or explicitly defines its own list by directly defining the various desired groups and group 'tuples'. No     OpenSSL FIPS modules are affected by this issue, the code in question lies outside the FIPS boundary.
    OpenSSL 3.6 and 3.5 are vulnerable to this issue. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2 once     it is released. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6 once it is released. OpenSSL 3.4, 3.3,     3.0, 1.0.2 and 1.1.1 are not affected by this issue. (CVE-2026-2673)

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

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

The remote Debian 12 / 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6201 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6201-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     April 07, 2026                        https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : openssl     CVE ID         : CVE-2026-2673 CVE-2026-28387 CVE-2026-28388 CVE-2026-28389                      CVE-2026-28390 CVE-2026-31789 CVE-2026-31790     Debian Bug     : 1130650

    Multiple vulnerabilities have been discovered in OpenSSL, a Secure     Sockets Layer toolkit, which may result in denial of service,     information leaks, or potentially remote code execution.

    Additional details can be found in the upstream advisory:
    https://openssl-library.org/news/secadv/20260407.txt

    For the oldstable distribution (bookworm), these problems have been fixed     in version 3.0.19-1~deb12u2.

    For the stable distribution (trixie), these problems have been fixed in     version 3.5.5-1~deb13u2.

    We recommend that you upgrade your openssl packages.

    For the detailed security status of openssl please refer to its security     tracker page at:
    https://security-tracker.debian.org/tracker/openssl

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian 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 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-47fffff581 advisory.

    Backport security patches from OpenSSL 3.5.6


Tenable has extracted the preceding description block directly from the Fedora 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
302500	OpenSSL 3.5.0 < 3.5.6 Multiple Vulnerabilities	Nessus	Web Servers	3/16/2026	4/14/2026	high
302501	OpenSSL 3.6.0 < 3.6.2 Multiple Vulnerabilities	Nessus	Web Servers	3/16/2026	4/14/2026	critical
310206	Fedora 44 : openssl (2026-d3e275d525)	Nessus	Fedora Local Security Checks	4/25/2026	4/25/2026	high
302192	FreeBSD : OpenSSL -- key agreement vulnerability (ee1e6a24-1eeb-11f1-81da-8447094a420f)	Nessus	FreeBSD Local Security Checks	3/13/2026	4/10/2026	high
302195	Linux Distros Unpatched Vulnerability : CVE-2026-2673	Nessus	Misc.	3/13/2026	4/19/2026	high
306090	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : OpenSSL vulnerabilities (USN-8155-1)	Nessus	Ubuntu Local Security Checks	4/13/2026	4/27/2026	critical
304598	Amazon Linux 2023 : openssl, openssl-devel, openssl-fips-provider-latest (ALAS2023-2026-1522)	Nessus	Amazon Linux Local Security Checks	4/1/2026	4/10/2026	high
307675	Debian dsa-6201 : libcrypto3-udeb - security update	Nessus	Debian Local Security Checks	4/21/2026	4/27/2026	critical
310585	Fedora 43 : openssl (2026-47fffff581)	Nessus	Fedora Local Security Checks	4/28/2026	4/28/2026	high

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