CVE-2026-59851

Libssh: libssh: authentication bypass via missing gssapi principal check

HIGH
8.8
CVSS Score
Published: July 21, 2026 at 02:20 PM UTC
Updated: August 17, 2026 at 10:34 PM UTC
3 products affected across 2 vendorsEnterprise LinuxHardened ImagesLibssh

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Severity
HIGH8.8
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions
Vendor states this is fixed in 0:0.12.0-3.el10_2 (unaffected)
Vendor states this is fixed in 8 (unaffected)
Vendor states this is fixed in 9 (unaffected)
Vendor states this is fixed in 0.12.1-4.hum1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

VDB Entryx_refsource_REDHATVendor Advisory
Source: cverecord
https://access.redhat.com/security/cve/CVE-2026-59851
Issue Trackingx_refsource_REDHATVendor Advisory
Source: cverecord
https://bugzilla.redhat.com/show_bug.cgi?id=2498184
Vendor Advisoryx_refsource_REDHATIssue Tracking
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:42922
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:55855

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.8HIGHredhat
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-863

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