Resource exhaustion in libssh - CVE-2026-59848

Vulnerability identifier: #VU139531

CSH Severity: Low

CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-59848

CWE-ID: CWE-400

Exploitation vector: Remote access

Exploit availability: No public exploit available

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

The vulnerability exists due to improper handling of unexpected responses in the sftp client response queue when processing server-supplied sftp response packets. A remote attacker can send response packets with unknown request IDs to cause a denial of service.

The issue affects the client side only.

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
Ubuntu
libssh (Ubuntu package)
libssh4-64bit
libssh4-64bit-debuginfo
libssh4-32bit
libssh4-32bit-debuginfo
libssh4
libssh4-debuginfo
libssh-debugsource
libssh-devel
libssh-config
libssh (Red Hat package)
Netezza Appliance - Cyclops

Install security update from vendor's website.

libssh - addressed in versions 0.11.5, 0.12.1
libssh (Ubuntu package) - addressed in versions 0.9.6-2ubuntu0.22.04.8, 0.10.6-2ubuntu0.5, 0.11.3-1ubuntu2.1
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 - 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-devel - 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 (Red Hat package) - addressed in versions 0.10.4-19.el9_8, 0.12.0-3.el10_2
Netezza Appliance - Cyclops - update to 11.3.1.4

• https://www.libssh.org/security/advisories/CVE-2026-59848.txt
• https://www.libssh.org/security/

• Multiple vulnerabilities in libssh
• SUSE update for libssh
• SUSE update for libssh
• Red Hat Enterprise Linux 10 update for libssh
• Ubuntu update for libssh
• Red Hat Enterprise Linux 9 update for libssh
• Multiple vulnerabilities in IBM Netezza Appliance - Cyclops