CVE-2026-40356

EUVD-2026-25993
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.
Wrap or Wraparound
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
mitreCNA
5.9 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mitkerberos_5
1.18 ≤
𝑥
< 1.22.3
CNA
Common Weakness Enumeration
References
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/