Vulnerability in the OpenSSH GSSAPI delta included in various Linux distributions. This vulnerability affects the GSSAPI patches added by various Linux distributions and does not affect the OpenSSH upstream project itself. The usage of sshpkt_disconnect() on an error, which does not terminate the process, allows an attacker to send an unexpected GSSAPI message type during the GSSAPI key exchange to the server, which will call the underlying function and continue the execution of the program without setting the related connection variables. As the variables are not initialized to NULL the code later accesses those uninitialized variables, accessing random memory, which could lead to undefined behavior. The recommended workaround is to use ssh_packet_disconnect() instead, which does terminate the process. The impact of the vulnerability depends heavily on the compiler flag hardening configuration.

redhat RHSA-2026:6463: RHSA-2026:6463: openssh security update (Important)

The remote CentOS Linux 9 host has packages installed that are affected by a vulnerability as referenced in the openssh-9.9p1-7.el9 build changelog.

  - Fix information disclosure or denial of service due to uninitialized variables in gssapi-keyex     (CVE-2026-3497)

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

The remote CentOS Linux 9 host has packages installed that are affected by a vulnerability as referenced in the openssh-9.9p1-5.el9 build changelog.

  - Fix information disclosure or denial of service due to uninitialized variables in gssapi-keyex     (CVE-2026-3497)

Note that Nessus has not tested for this issue 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 multiple vulnerabilities as referenced in the FEDORA-2026-62fb46caac advisory.

    - CVE-2026-3497: Fix information disclosure or denial of service due to uninitialized variables in gssapi-     keyex

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.

The remote Fedora 42 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-39819a3d62 advisory.

    - CVE-2026-3497: Fix information disclosure or denial of service due to uninitialized variables in gssapi-     keyex

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.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-bab4aa5da7 advisory.

    - CVE-2026-3497: Fix information disclosure or denial of service due to uninitialized variables in gssapi-     keyex

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.

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-8090-1 advisory.

    Jeremy Brown discovered that the OpenSSH GSSAPI Key Exchange incorrectly handled disconnecting clients. In     non-default configurations where the GSSAPIKeyExchange setting is enabled, a remote attacker could use     this issue to cause OpenSSH to crash, resulting in a denial of service, or possibly execute arbitrary     code. (CVE-2026-3497)

    David Leadbeater discovered that OpenSSH incorrectly handled certain control characters in usernames. When     untrusted usernames and the ProxyCommand are being used, an attacker could possibly use this issue to     execute arbitrary code. (CVE-2025-61984)

    David Leadbeater discovered that OpenSSH incorrectly handled NULL characters in ssh:// URIs. When the     ProxyCommand is being used, an attacker could possibly use this issue to execute arbitrary code.
    (CVE-2025-61985)

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

  - Vulnerability in the OpenSSH GSSAPI delta included in various Linux distributions. This vulnerability     affects the GSSAPI patches added by various Linux distributions and does not affect the OpenSSH upstream     project itself. The usage of sshpkt_disconnect() on an error, which does not terminate the process, allows     an attacker to send an unexpected GSSAPI message type during the GSSAPI key exchange to the server, which     will call the underlying function and continue the execution of the program without setting the related     connection variables. As the variables are not initialized to NULL the code later accesses those     uninitialized variables, accessing random memory, which could lead to undefined behavior. The recommended     workaround is to use ssh_packet_disconnect() instead, which does terminate the process. The impact of the     vulnerability depends heavily on the compiler flag hardening configuration. (CVE-2026-3497)

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

ID	Name	Product	Family	Severity
304416	CentOS 9 : openssh-9.9p1-7.el9	Nessus	CentOS Local Security Checks	medium
303361	CentOS 9 : openssh-9.9p1-5.el9	Nessus	CentOS Local Security Checks	medium
303279	Fedora 44 : openssh (2026-62fb46caac)	Nessus	Fedora Local Security Checks	medium
303246	Fedora 42 : openssh (2026-39819a3d62)	Nessus	Fedora Local Security Checks	medium
303121	Fedora 43 : openssh (2026-bab4aa5da7)	Nessus	Fedora Local Security Checks	medium
302216	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : OpenSSH vulnerabilities (USN-8090-1)	Nessus	Ubuntu Local Security Checks	medium
302159	Linux Distros Unpatched Vulnerability : CVE-2026-3497	Nessus	Misc.	medium

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