Debian dla-4773 : libssh2-1 - security update

high Nessus Plugin ID 343114

Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4773 advisory.

------------------------------------------------------------------------- Debian LTS Advisory DLA-4773-1 [email protected] https://www.debian.org/lts/security/ Emmanuel Arias September 05, 2026 https://wiki.debian.org/LTS
-------------------------------------------------------------------------

Package : libssh2 Version : 1.10.0-3+deb12u1 CVE ID : CVE-2025-15661 CVE-2026-7598 CVE-2026-58050 CVE-2026-58051 CVE-2026-66032 CVE-2026-66034 Debian Bug : 1140401 1142856 1144415

Multiple security vulnerabilities were discovered in libssh2, a client-side C library implementing the SSH2 protocol which could result in memory disclosure, denial of service or potentially the execution of arbitrary code.

CVE-2025-15661

A malicious server could send an oversized link_len in SSH_FXP_NAME responses (READLINK/REALPATH) and trigger an out-of-bounds memcpy, leaking heap memory or crashing the client

CVE-2026-7598

The impacted element is the function userauth_password of the file src/userauth.c. Such manipulation of the argument

CVE-2026-58050

libsshw2 reads an attacker-controlled 32-bit attribute without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. count from a publickey-subsystem response and uses it without bounds checking, causing an overflows to an undersized buffer

CVE-2026-58051

libssh2 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. 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-2026-66032

Fix double free in sftp_open() reachable from a malicious server during SFTP session setup (SSH_FXP_OPEN answered with SSH_FXP_STATUS/FX_OK followed by a failing sftp_packet_require()) (Closes:

CVE-2026-66034

Fix missing bounds check in libssh2_publickey_list_fetch() leading to a heap out-of-bounds read and a free of an uninitialized pointer, triggerable by a malicious server via the publickey subsystem.

For Debian 12 bookworm, these problems have been fixed in version 1.10.0-3+deb12u1.

We recommend that you upgrade your libssh2 packages.

For the detailed security status of libssh2 please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/libssh2

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS Attachment:
signature.asc Description: PGP signature

Tenable has extracted the preceding description block directly from the Debian 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

Upgrade the libssh2-1 packages.

Plugin Details

Severity: High

ID: 343114

File Name: debian_DLA-4773.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Debian Local Security Checks

Published: 9/5/2026

Updated: 9/5/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.9

Percentile: 96.76

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.9

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

CVSS Score Source: CVE-2026-7598

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.9

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

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

CVSS Score Source: CVE-2025-15661

CVSS v4

Risk Factor: High

Base Score: 8.7

Threat Score: 7.4

Threat Vector: CVSS:4.0/E:P

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

CVSS Score Source: CVE-2026-66032

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:12.0, p-cpe:/a:debian:debian_linux:libssh2-1-dev, p-cpe:/a:debian:debian_linux:libssh2-1

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/5/2026

Vulnerability Publication Date: 5/1/2026

Reference Information

CVE: CVE-2025-15661, CVE-2026-58050, CVE-2026-58051, CVE-2026-66032, CVE-2026-66034, CVE-2026-7598

Detections

Analytics