Quick answers
- Is CVE-2026-59849 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-59849 being exploited in the wild.
- How severe is CVE-2026-59849?
- Low severity, with a CVSS score of 3.1, published 21 July 2026.
- Which products and versions are affected?
- Libssh unspecified.
- Is there a fix for CVE-2026-59849?
- 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-2026-59849 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-59849?
- 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
A vulnerability exists in the ssh_userauth_publickey_auto() function within src/auth.c of libssh. The issue stems from a logic error where the iterator over certificate candidates is not correctly advanced when certificates are missing or repeatedly rejected by the server. Under specific non-default certificate configurations, this causes the client to restart the same authentication attempts indefinitely (CWE-835). An attacker or a misconfigured server could trigger this infinite loop, resulting in a denial of service for the libssh client. The vulnerability requires a network-reachable client and specific authentication preconditions.
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: Reported to Red Hat Bugzilla
- 2026-07-21: disclosed: CVE published to NVD