CVE-2026-59851
Libssh: libssh: authentication bypass via missing gssapi principal check
A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users.
Fixes and workarounds
Workaround
Disable GSSAPIKeyExchange.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat Enterprise Linux 10 Red Hat libssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:0.12.0-3.el10_2; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Hardened Images Red Hat libssh-main
https://catalog.redhat.com/software/containers/ |
≥ 0.12.1-4.hum1; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat libssh
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat libssh
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
NVD applicability configurations (1)
These expressions retain AND/OR operators, negation, and required environmental products. A listed product is not sufficient to establish exposure when additional conditions apply.
[
{
"negate": false,
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:libssh:libssh:-:*:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "OR"
}
]CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 8.8 high |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | CNA: redhat |
| 3.1 / 8.8 high |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/errata/RHSA-2026:42922CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:55855CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-59851CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2498184CNA: redhat · issue-tracking, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:42922[email protected] · Issue Tracking
- https://access.redhat.com/errata/RHSA-2026:55855[email protected]
- https://access.redhat.com/security/cve/CVE-2026-59851[email protected] · Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2498184[email protected] · Issue Tracking, Vendor Advisory
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