NULL Pointer Dereference in MIT Kerberos 5 Affects Unix Systems
CVE-2026-40355

5.9MEDIUM

Key Information:

Vendor

Mit

Status
Kerberos 5
Vendor
CVE Published:
28 April 2026

What is CVE-2026-40355?

A vulnerability in MIT Kerberos 5 prior to version 1.22.3 allows an unauthenticated remote attacker to exploit a NULL pointer dereference when calling gss_accept_sec_context(). This issue arises in systems using a NegoEx mechanism registered in the /etc/gss/mech file. An attacker can trigger the problem, resulting in a termination of the process during the parse_nego_message phase.

Affected Version(s)

Kerberos 5 1.18 < 1.22.3

References

https://web.mit.edu/kerberos/advisories/
https://cems.fun/2026/04/27/krb5-two-unauthenticated-netw...
https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc9...

CVSS V3.1

Score:
5.9
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.