Quick answers
- Is CVE-2026-59851 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-59851 being exploited in the wild.
- How severe is CVE-2026-59851?
- High severity, with a CVSS score of 8.8, published 21 July 2026.
- Which products and versions are affected?
- Libssh unspecified.
- Is there a fix for CVE-2026-59851?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-59851 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-59851?
- Check whether you run Libssh at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An authorization bypass exists in libssh's server-side GSSAPIKeyExchange implementation within `ssh_packet_userauth_request()` in `src/messages.c`. When `GSSAPIKeyExchange` is enabled, the `gssapi-keyex` authentication path grants access immediately after successful Kerberos authentication without executing the necessary callback to verify if the authenticated principal is authorized for the requested local username. A remote attacker with valid Kerberos credentials can exploit this to log in as any local user, including root, bypassing intended access controls. The vulnerability is tracked as CWE-863 (Incorrect Authorization).
Affected products
- libssh libssh unspecified
- Red Hat Red Hat Enterprise Linux 10 affected
- Red Hat Red Hat Hardened Images affected
Timeline
- 2026-07-08: other: Initial report in Red Hat Bugzilla
- 2026-07-21: disclosed: CVE published to NVD