In sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over PermitTunnel=yes, but did not.

An update of the openssh package has been released.

The remote Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8533-1 advisory.

    It was discovered that OpenSSH sftp did not properly constrain the location of downloaded files when     connecting to an attacker-controlled server. An attacker could possibly use this issue to write files to     unintended locations on the file system. (CVE-2026-59995)

    It was discovered that OpenSSH scp could place files in the parent directory of the intended destination     when copying between two remote hosts. An attacker could possibly use this issue to write files to     unintended locations. (CVE-2026-59996)

    It was discovered that OpenSSH internal-sftp only recognized the first nine command-line arguments, This     could result in certain security-sensitive arguments being ignored, contrary to expectations.
    (CVE-2026-59997)

    It was discovered that OpenSSH had undocumented behaviour regarding the GSSAPIStrictAcceptorCheck option     in environments using Windows Active Directory. The documentation has been updated to clarify use of the     option. (CVE-2026-59998)

    It was discovered that OpenSSH did not properly enforce precedence of DisableForwarding=yes over     PermitTunnel=yes in server configurations. This could possibly result in intended network forwarding     restrictions being bypassed, contrary to expectations. (CVE-2026-59999)

    It was discovered that OpenSSH mishandled the MaxAuthTries limit for GSSAPI authentication. A remote     attacker could use this issue to perform excessive authentication attempts. (CVE-2026-60000)

    It was discovered that OpenSSH did not always honour the minimum authentication delay. An attacker could     possibly use this issue to perform brute-force attacks more efficiently. (CVE-2026-60001)

    It was discovered that the OpenSSH client had a use-after-free vulnerability when a server changed its     host key during a key re-exchange. An attacker able to intercept communications could possibly use this     issue to execute arbitrary code or obtain sensitive information. (CVE-2026-60002)

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 version of OpenSSH installed on the remote host is prior to 10.4. It is, therefore, affected by multiple vulnerabilities, including:

  - ssh in OpenSSH before 10.4 can have a use-after-free when a server changes its host key during a key     re-exchange. This outcome occurs only on the client side. (CVE-2026-60002)

  - sshd in OpenSSH before 10.4 does not always honor the minimum authentication delay. (CVE-2026-60001)

  - In sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over     PermitTunnel=yes, but did not. (CVE-2026-59999)

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.

  - In sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over     PermitTunnel=yes, but did not. (CVE-2026-59999)

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

ID	Name	Product	Family	Severity
328777	Photon OS 5.0: Openssh PHSA-2026-5.0-0926	Nessus	PhotonOS Local Security Checks	critical
326800	Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenSSH vulnerabilities (USN-8533-1)	Nessus	Ubuntu Local Security Checks	critical
326244	OpenSSH < 10.4 Multiple Vulnerabilities	Nessus	Misc.	critical
325682	Linux Distros Unpatched Vulnerability : CVE-2026-59999	Nessus	Misc.	high

Detections

Analytics

CVE-2026-59999

high

Tenable Plugins

critical

critical

critical

high