Libssh: libssh: denial of service via inefficient regular expression processing
Summary
| CVE | CVE-2026-0967 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-26 21:17:00 UTC |
| Updated | 2026-04-02 17:28:27 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 5.5 MEDIUM from [email protected]
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
EPSS: 0.000680000 probability, percentile 0.208430000 (date 2026-04-01)
Problem Types: CWE-1333 | CWE-1333 Inefficient Regular Expression Complexity
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 5.5 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H |
| 3.0 | [email protected] | Secondary | 2.2 | LOW | CVSS:3.0/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L |
| 3.0 | CNA | CVSS | 2.2 | LOW | CVSS:3.0/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L |
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
NoneUser Interaction
RequiredScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS v3.0 Breakdown
Attack Vector
LocalAttack Complexity
HighPrivileges Required
LowUser Interaction
RequiredScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
LowCVSS:3.0/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Libssh | Libssh | All | All | All | All |
| Operating System | Redhat | Enterprise Linux | 10.0 | All | All | All |
| Operating System | Redhat | Enterprise Linux | 9.0 | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | Third Party Advisory |
| www.libssh.org/2026/02/10/libssh-0-12-0-and-0-11-4-security-releases | [email protected] | www.libssh.org | Release Notes |
| access.redhat.com/security/cve/CVE-2026-0967 | [email protected] | access.redhat.com | Third Party Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank Jakub Jelen (libssh) and Kang Yang for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-02-04T23:43:23.869Z | Reported to Red Hat. |
| CNA | 2026-02-10T18:47:09.215Z | Made public. |
Workarounds
CNA: Avoid using complex patterns in configuration files and known_hosts.
There are currently no legacy QID mappings associated with this CVE.