sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has no value if the server is in Windows Active Directory.

The remote Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8804-1 advisory.

    Florian Kohnhuser discovered that OpenSSH incorrectly handled shell metacharacters in certain usernames.
    An attacker could possibly use this issue to execute arbitrary commands when certain non-default     configurations were used, resulting in arbitrary code execution. This issue only affected Ubuntu 14.04     LTS. (CVE-2026-35386)

    Christos Papakonstantinou discovered that OpenSSH incorrectly handled ECDSA algorithm restrictions. An     attacker could possibly use this issue to cause unintended ECDSA algorithms to be accepted, resulting in     security restrictions being bypassed. (CVE-2026-35387)

    Vladimir Tokarev discovered that OpenSSH incorrectly handled certain principal restrictions in     authorized_keys files. An attacker could possibly use this issue to bypass principal restrictions,     resulting in unauthorized access. This issue only affected Ubuntu 14.04 LTS, Ubuntu 18.04 LTS, and Ubuntu     20.04 LTS. (CVE-2026-35414)

    It was discovered that OpenSSH incorrectly handled downloaded file paths when using sftp with an untrusted     server. An attacker could possibly use this issue to write downloaded files outside the intended location,     resulting in unauthorized file modification. (CVE-2026-59995)

    It was discovered that OpenSSH incorrectly handled command-line arguments in internal-sftp. An attacker     could possibly use this issue to cause certain security-related arguments to be ignored, resulting in     security restrictions being bypassed. (CVE-2026-59997)

    It was discovered that OpenSSH incorrectly handled GSSAPIStrictAcceptorCheck when used with Windows Active     Directory. An attacker could possibly use this issue to bypass GSSAPI security restrictions, resulting in     unauthorized access. (CVE-2026-59998)

    It was discovered that OpenSSH incorrectly handled forwarding restrictions when DisableForwarding and     PermitTunnel were used together. An attacker could possibly use this issue to create tunnels despite     forwarding being disabled, resulting in security restrictions being bypassed. This issue only affected     Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-59999)

    It was discovered that OpenSSH incorrectly handled authentication attempt limits when using GSSAPI     authentication. An attacker could possibly use this issue to consume excessive system resources, resulting     in a denial of service. (CVE-2026-60000)

    It was discovered that OpenSSH did not always enforce the minimum authentication delay. An attacker could     possibly use this issue to perform authentication attempts more rapidly than intended, resulting in     weakened brute-force protections. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-60001)

    It was discovered that OpenSSH incorrectly handled certain concurrent remote forwarding operations. An     attacker could possibly use this issue to trigger a use-after-free, resulting in a denial of service or     arbitrary code execution. (CVE-2026-73282)

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 SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:3605-1 advisory.

    - Backported support for the mlkemx25519 key exchange from upstream (jsc#PED-16473).

    - CVE-2026-59995: sftp: location of downloaded files not properly constrained when `sftp server:/path .`     is used with       an attacker-controlled server (bsc#1271044).
    - CVE-2026-59996: scp: file placed in the parent directory of an intended target directory when copy     occurs between two       remote destinations (bsc#1271046).
    - CVE-2026-59997: sshd: `internal-sftp` command lines are silently truncated after the 9th argument     (bsc#1271048).
    - CVE-2026-59998: sshd: undocumented security-relevant `GSSAPIStrictAcceptorCheck` behavior in Windows     Active Directory       is not documented (bsc#1271049).
    - CVE-2026-59999: sshd: `DisableForwarding=yes` does not override `PermitTunnel=yes` (bsc#1271052).
    - CVE-2026-60000: sshd: pre-authentication denial of service when GSSAPIAuthentication is enabled     (bsc#1271053).
    - CVE-2026-60001: sshd: minimum authentication delay is not honored (bsc#1271054).
    - CVE-2026-60002: ssh: client-side use-after-free when a server changes its host key during a key     reexchange       (bsc#1271055).

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

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

An update of the openssh package has been released.

The remote openSUSE 16 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:21477-1 advisory.

    - CVE-2026-59995: sftp: location of downloaded files not properly constrained when `sftp server:/path .`     is used with       an attacker-controlled server (bsc#1271044).
    - CVE-2026-59996: scp: file placed in the parent directory of an intended target directory when copy     occurs between two       remote destinations (bsc#1271046).
    - CVE-2026-59997: sshd: `internal-sftp` command lines are silently truncated after the 9th argument     (bsc#1271048).
    - CVE-2026-59998: sshd: undocumented security-relevant `GSSAPIStrictAcceptorCheck` behavior in Windows     Active Directory       is not documented (bsc#1271049).
    - CVE-2026-59999: sshd: `DisableForwarding=yes` does not override `PermitTunnel=yes` (bsc#1271052).
    - CVE-2026-60000: sshd: pre-authentication denial of service when GSSAPIAuthentication is enabled     (bsc#1271053).
    - CVE-2026-60001: sshd: minimum authentication delay is not honored (bsc#1271054).
    - CVE-2026-60002: ssh: client-side use-after-free when a server changes its host key during a key     reexchange       (bsc#1271055).

Tenable has extracted the preceding description block directly from the SUSE 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 / 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.

  - sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has     no value if the server is in Windows Active Directory. (CVE-2026-59998)

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

ID	Name	Product	Family	Type	Severity
349265	Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS : OpenSSH vulnerabilities (USN-8804-1)	Nessus	Ubuntu Local Security Checks	Local	high
335328	SUSE SLED15: openssh / openssh-askpass-gnome / openssh-clients / openssh-common / etc (SUSE-SU-2026:3605-1)	Nessus	SuSE Local Security Checks	Local	critical
333942	Photon OS 5.0: Openssh PHSA-2026-5.0-92-0926	Nessus	PhotonOS Local Security Checks	Local	critical
331565	openSUSE 16: openssh / openssh-askpass-gnome / openssh-cavs / openssh-clients / etc (openSUSE-SU-2026:21477-1)	Nessus	SuSE Local Security Checks	Local	critical
328777	Photon OS 5.0: Openssh PHSA-2026-5.0-0926	Nessus	PhotonOS Local Security Checks	Local	critical
326800	Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenSSH vulnerabilities (USN-8533-1)	Nessus	Ubuntu Local Security Checks	Local	critical
326244	OpenSSH < 10.4 Multiple Vulnerabilities	Nessus	Misc.	Remote	critical
325680	Linux Distros Unpatched Vulnerability : CVE-2026-59998	Nessus	Misc.	Local	medium

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