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Amazon Linux 2023 : libssh2, libssh2-devel (ALAS2023-2026-1966)

high Nessus Plugin ID 328482

Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

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.

Solution

Run 'dnf update libssh2 --releasever 2023.12.20260720' or or 'dnf update --advisory ALAS2023-2026-1966 --releasever 2023.12.20260720' to update your system.

See Also

https://alas.aws.amazon.com//AL2023/ALAS2023-2026-1966.html

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2026-58050.html

https://explore.alas.aws.amazon.com/CVE-2026-58051.html

Plugin Details

Severity: High

ID: 328482

File Name: al2023_ALAS2023-2026-1966.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 7/20/2026

Updated: 7/20/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.5

Percentile: 96.32

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.1

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

CVSS Score Source: CVE-2026-58050

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.7

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

CVSS v4

Risk Factor: High

Base Score: 8.3

Threat Score: 6.9

Threat Vector: CVSS:4.0/E:P

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

CVSS Score Source: CVE-2026-58051

Vulnerability Information

CPE: cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:libssh2-debuginfo, p-cpe:/a:amazon:linux:libssh2-debugsource, p-cpe:/a:amazon:linux:libssh2-devel, p-cpe:/a:amazon:linux:libssh2-docs, p-cpe:/a:amazon:linux:libssh2

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 7/20/2026

Vulnerability Publication Date: 6/28/2026

Reference Information

CVE: CVE-2026-58050, CVE-2026-58051