CVE-2026-40356 PUBLISHED

Assigner: mitre
Reserved: 11.04.2026 Published: 28.04.2026 Updated: 28.04.2026

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.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 5.9

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	MIT
Product	Kerberos 5
Versions	Default: unaffected affected from 1.18 to 1.22.3 (excl.)

References

https://web.mit.edu/kerberos/advisories/
https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f

Problem Types

CWE-191 Integer Underflow (Wrap or Wraparound) CWE