CVE-2026-0967: Libssh: libssh: denial of service via inefficient regular expression processing

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-26 · updated 2026-09-01
Weakness: CWE-1333

Description

A flaw was found in libssh. A remote attacker, by controlling client configuration files or known_hosts files, could craft specific hostnames that when processed by the `match_pattern()` function can lead to inefficient regular expression backtracking. This can cause timeouts and resource exhaustion, resulting in a Denial of Service (DoS) for the client.

Affected products

libssh: through 0.11.3
Red Hat Enterprise Linux: 9.0, 10.0

References

https://access.redhat.com/errata/RHSA-2026:18160
https://access.redhat.com/errata/RHSA-2026:18683
https://access.redhat.com/security/cve/CVE-2026-0967
https://bugzilla.redhat.com/show_bug.cgi?id=2436981
https://www.libssh.org/2026/02/10/libssh-0-12-0-and-0-11-4-security-releases/

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