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[USN-8051-2] libssh vulnerabilities

Posted on 23 February 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8051-2
February 23, 2026

libssh vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in libssh.

Software Description:
- libssh: A tiny C SSH library

Details:

USN-8051-1 fixed vulnerabilities in libssh. This update provides the
corresponding updates for Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu
20.04 LTS.

Original advisory details:

It was discovered that libssh clients incorrectly handled the key exchange
process. A remote attacker could possibly use this issue to cause libssh
clients to crash, resulting in a denial of service. (CVE-2025-8277)

It was discovered that the libssh SCP client incorrectly sanitized paths
received from servers. A remote attacker could use this issue to cause
libssh SCP clients to overwrite files outside of the working directory and
possibly execute arbitrary code. (CVE-2026-0964)

It was discovered that libssh incorrectly handled parsing configuration
files. A local attacker could possibly use this issue to cause libssh to
access non-regular files, resulting in a denial of service. (CVE-2026-0965)

It was discovered that libssh incorrectly handled the ssh_get_hexa()
function. A remote attacker could possibly use this issue to cause libssh
to crash, resulting in a denial of service. (CVE-2026-0966)

It was discovered that libssh incorrectly handled certain regular
expressions. A local attacker could possibly use this issue to cause
libssh to consume resources, resulting in a denial of service.
(CVE-2026-0967)

It was discovered that the libssh SFTP client incorrectly handled certain
malformed longname fields. A remote attacker could use this issue to cause
libssh SFTP clients to crash, resulting in a denial of service, or
possibly execute arbitrary code. (CVE-2026-0968)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 20.04 LTS
libssh-4 0.9.3-2ubuntu2.5+esm3
Available with Ubuntu Pro

Ubuntu 18.04 LTS
libssh-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6
Available with Ubuntu Pro

Ubuntu 16.04 LTS
libssh-4 0.6.3-4.3ubuntu0.6+esm4
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8051-2
https://ubuntu.com/security/notices/USN-8051-1
CVE-2025-8277, CVE-2026-0964, CVE-2026-0965, CVE-2026-0966,
CVE-2026-0967, CVE-2026-0968

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