Authentication Bypass Flaw in libssh Affects Multiple Server Environments
CVE-2026-59851

8.8HIGH

Key Information:

Vendor

Red Hat
Status
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat Hardened Images
Vendor
CVE Published:
21 July 2026

What is CVE-2026-59851?

A security issue has been identified in libssh, specifically affecting servers with the GSSAPIKeyExchange feature enabled. The flaw occurs in the gssapi-keyex path, where it does not properly verify if the authenticated Kerberos principal is authorized to access the intended local user account. This vulnerability permits authenticated clients to log in as other users without proper authorization, potentially leading to unauthorized access and privilege escalation.

References

https://access.redhat.com/security/cve/CVE-2026-59851
vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2498184
issue-trackingx_refsource_REDHAT

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Red Hat would like to thank Aisle Research for reporting this issue.
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