CVE-2026-40356
Description
In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| rhel | 9 | fixed | |
| debian | bookworm | fixed | 1.20.1-2+deb12u5 |
| debian | forky | fixed | 1.22.1-2.1 |
| debian | sid | fixed | 1.22.1-2.1 |
| debian | trixie | fixed | 1.21.3-5+deb13u1 |
| sles | affected | | |
| debian | bullseye | fixed | 1.18.3-6+deb11u8 |
References
- https://access.redhat.com/errata/RHSA-2026:19357
- https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
- https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f
- https://web.mit.edu/kerberos/advisories/
- https://security-tracker.debian.org/tracker/CVE-2026-40356
- https://www.suse.com/security/cve/CVE-2026-40356.html
- https://access.redhat.com/errata/RHSA-2026:16799
- https://bugzilla.redhat.com/2463368
- https://bugzilla.redhat.com/2463370
- https://errata.almalinux.org/8/ALSA-2026-16799.html
- https://errata.almalinux.org/9/ALSA-2026-19357.html
CWEs
CWE-191
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.