Use-after-free in libssh - CVE-2026-59850

Vulnerability identifier: #VU139533

CSH Severity: Low

CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-59850

CWE-ID: CWE-416

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to use-after-free in channel data callbacks when processing data on closed channels. A remote user can send data through a closed channel to cause a denial of service.

The issue affects both server and client components and is exemplified on SFTP channels.

libssh
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Micro
SUSE Linux Enterprise Micro for Rancher
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Basesystem Module
openSUSE Leap
openEuler
Ubuntu
Anolis OS
libssh
libssh-debuginfo
libssh-debugsource
libssh-devel
libssh-help
libssh (Ubuntu package)
libssh4-32bit
libssh4-64bit
libssh4-64bit-debuginfo
libssh4-32bit-debuginfo
libssh4
libssh4-debuginfo
libssh-config
libssh (Red Hat package)
libssh-doc

Install security update from vendor's website.

libssh - addressed in versions 0.11.5, 0.12.1
libssh - addressed in versions 0.9.4-21, 0.9.6-21, 0.10.5-15
libssh-debuginfo - addressed in versions 0.9.4-21, 0.9.6-21, 0.10.5-15
libssh-debugsource - addressed in versions 0.9.4-21, 0.9.6-21, 0.10.5-15
libssh-devel - addressed in versions 0.9.4-21, 0.9.6-21, 0.10.5-15
libssh-help - addressed in versions 0.9.4-21, 0.9.6-21, 0.10.5-15
libssh (Ubuntu package) - addressed in versions 0.9.6-2ubuntu0.22.04.8, 0.10.6-2ubuntu0.5, 0.11.3-1ubuntu2.1
libssh4-32bit - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh4-64bit - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh4-64bit-debuginfo - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh4-32bit-debuginfo - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh4 - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh4-debuginfo - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh-debugsource - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh-config - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh-devel - addressed in versions 0.9.8-150400.3.20.1, 0.9.8-150600.11.15.1
libssh (Red Hat package) - addressed in versions 0.10.4-19.el9_8, 0.12.0-3.el10_2
libssh - update to 0.10.5-16
libssh-devel - update to 0.10.5-16
libssh-config - update to 0.10.5-16
libssh-doc - update to 0.10.5-16

• https://www.libssh.org/security/advisories/CVE-2026-59850.txt
• https://www.libssh.org/security/

• Multiple vulnerabilities in libssh
• SUSE update for libssh
• SUSE update for libssh
• Anolis OS update for libssh
• openEuler 24.03 LTS SP3 update for libssh
• openEuler 24.03 LTS SP1 update for libssh
• openEuler 22.03 LTS SP4 update for libssh
• openEuler 20.03 LTS SP4 update for libssh
• Red Hat Enterprise Linux 10 update for libssh
• openEuler 24.03 LTS SP4 update for libssh
• Ubuntu update for libssh
• Red Hat Enterprise Linux 9 update for libssh