The API function `ssh_get_hexa()` is vulnerable, when 0-lenght input is provided to this function. This function is used internally in `ssh_get_fingerprint_hash()` and `ssh_print_hexa()` (deprecated), which is vulnerable to the same input (length is provided by the calling application). The function is also used internally in the gssapi code for logging the OIDs received by the server during GSSAPI authentication. This could be triggered remotely, when the server allows GSSAPI authentication and logging verbosity is set at least to SSH_LOG_PACKET (3). This could cause self-DoS of the per-connection daemon process.

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1461 advisory.

    libssh: Buffer underflow in ssh_get_hexa() on invalid input (CVE-2026-0966)

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 SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 / openSUSE 15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:0779-1 advisory.

    - CVE-2026-0964: improper sanitation of paths received from SCP servers can cause path traversal     (bsc#1258049).
    - CVE-2026-0965: possible denial of service when parsing unexpected configuration files (bsc#1258045).
    - CVE-2026-0966: buffer underflow in ssh_get_hexa() on invalid input (bsc#1258054).
    - CVE-2026-0967: specially crafted patterns could cause denial of service (bsc#1258081).
    - CVE-2026-0968: malformed SFTP message can lead to out of bound read (bsc#1258080).

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 SUSE Linux SLES12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:0778-1 advisory.

    - CVE-2026-0964: improper sanitation of paths received from SCP servers can cause path traversal     (bsc#1258049).
    - CVE-2026-0965: possible denial of service when parsing unexpected configuration files (bsc#1258045).
    - CVE-2026-0966: buffer underflow in ssh_get_hexa() on invalid input (bsc#1258054).
    - CVE-2026-0967: specially crafted patterns could cause denial of service (bsc#1258081).
    - CVE-2026-0968: malformed SFTP message can lead to out of bound read (bsc#1258080).

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 / 25.10 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8051-1 advisory.

    It was discovered that libssh clients incorrectly handled the key exchange process. A remote attacker     could possibly use this issue to cause libssh clients to crash, resulting in a denial of service.
    (CVE-2025-8277)

    It was discovered that the libssh SCP client incorrectly sanitized paths received from servers. A remote     attacker could use this issue to cause libssh SCP clients to overwrite files outside of the working     directory and possibly execute arbitrary code. (CVE-2026-0964)

    It was discovered that libssh incorrectly handled parsing configuration files. A local attacker could     possibly use this issue to cause libssh to access non-regular files, resulting in a denial of service.
    (CVE-2026-0965)

    It was discovered that libssh incorrectly handled the ssh_get_hexa() function. A remote attacker could     possibly use this issue to cause libssh to crash, resulting in a denial of service. (CVE-2026-0966)

    It was discovered that libssh incorrectly handled certain regular expressions. A local attacker could     possibly use this issue to cause libssh to consume resources, resulting in a denial of service.
    (CVE-2026-0967)

    It was discovered that the libssh SFTP client incorrectly handled certain malformed longname fields. A     remote attacker could use this issue to cause libssh SFTP clients to crash, resulting in a denial of     service, or possibly execute arbitrary code. (CVE-2026-0968)

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 libssh installed on the remote host is prior to 0.11.4 / 0.12.0. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2026-047-01 advisory.

    New libssh packages are available for Slackware 15.0 and -current to fix security issues.

Tenable has extracted the preceding description block directly from the libssh 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.

  - The API function `ssh_get_hexa()` is vulnerable, when 0-lenght input is provided to this function. This     function is used internally in `ssh_get_fingerprint_hash()` and `ssh_print_hexa()` (deprecated), which is     vulnerable to the same input (length is provided by the calling application). The function is also used     internally in the gssapi code for logging the OIDs received by the server during GSSAPI authentication.
    This could be triggered remotely, when the server allows GSSAPI authentication and logging verbosity is     set at least to SSH_LOG_PACKET (3). This could cause self-DoS of the per-connection daemon process.
    (CVE-2026-0966)

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

ID	Name	Product	Family	Severity
301351	Amazon Linux 2023 : libssh, libssh-config, libssh-devel (ALAS2023-2026-1461)	Nessus	Amazon Linux Local Security Checks	medium
301025	SUSE SLED15 / SLES15 / openSUSE 15 Security Update : libssh (SUSE-SU-2026:0779-1)	Nessus	SuSE Local Security Checks	medium
301023	SUSE SLES12 Security Update : libssh (SUSE-SU-2026:0778-1)	Nessus	SuSE Local Security Checks	medium
299636	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : libssh vulnerabilities (USN-8051-1)	Nessus	Ubuntu Local Security Checks	low
299277	Slackware Linux 15.0 / current libssh Multiple Vulnerabilities (SSA:2026-047-01)	Nessus	Slackware Local Security Checks	high
298574	Linux Distros Unpatched Vulnerability : CVE-2026-0966	Nessus	Misc.	medium

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