libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.

The version of libssh2 installed on the remote host is prior to 1.4.3-12. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3813 advisory.

    libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem     response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds     checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH     server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer     overflow in a connecting libssh2 client. (CVE-2026-58050)

    libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries     before parsing populates them, so a parse failure reaching the cleanup path leaves     libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the     publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-     influenceable attrs pointer in a connecting libssh2 client. (CVE-2026-58051)

Tenable has extracted the preceding description block directly from the tested product 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 multiple vulnerabilities as referenced in the ALAS2023-2026-1966 advisory.

    libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem     response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds     checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH     server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer     overflow in a connecting libssh2 client. (CVE-2026-58050)

    libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries     before parsing populates them, so a parse failure reaching the cleanup path leaves     libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the     publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-     influenceable attrs pointer in a connecting libssh2 client. (CVE-2026-58051)

Tenable has extracted the preceding description block directly from the tested product 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 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8532-1 advisory.

    It was discovered that libssh2 incorrectly handled certain publickey subsystem attributes. A remote     attacker controlling a malicious SSH server could use this issue to cause a denial of service or possibly     execute arbitrary code. (CVE-2026-58050)

    It was discovered that libssh2 did not properly initialize publickey list entries before parsing. A remote     attacker controlling a malicious SSH server could use this issue to cause a denial of service or possibly     execute arbitrary code. (CVE-2026-58051)

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 Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0572 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2026-58051:
    libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries     before parsing populates them, so a parse failure reaching the cleanup path leaves     libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the     publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-     influenceable attrs pointer in a connecting libssh2 client.

    CVE-2026-58050:
    libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem     response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds     checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH     server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer     overflow in a connecting libssh2 client.

Tenable has extracted the preceding description block directly from the Tencent Linux 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.

  - libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries     before parsing populates them, so a parse failure reaching the cleanup path leaves     libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the     publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-     influenceable attrs pointer in a connecting libssh2 client. (CVE-2026-58051)

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

ID	Name	Product	Family	Severity
328836	Amazon Linux 2 : libssh2, --advisory ALAS2-2026-3813 (ALAS-2026-3813)	Nessus	Amazon Linux Local Security Checks	high
328482	Amazon Linux 2023 : libssh2, libssh2-devel (ALAS2023-2026-1966)	Nessus	Amazon Linux Local Security Checks	high
326802	Ubuntu 24.04 LTS / 26.04 LTS : libssh2 vulnerabilities (USN-8532-1)	Nessus	Ubuntu Local Security Checks	high
325859	TencentOS Server 4: libssh2 (TSSA-2026:0572)	Nessus	Tencent Local Security Checks	high
323570	Linux Distros Unpatched Vulnerability : CVE-2026-58051	Nessus	Misc.	high

Detections

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CVE-2026-58051

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Tenable Plugins

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