CVE-2026-40356

Severity CVSS v4.0:

Pending analysis

Type:

CWE-191 Integer Underflow (Wrap or Wraparound)

Publication date:

28/04/2026

Last modified:

28/04/2026

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.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 5.90 MEDIUM
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x

5.90

Severity 3.x

MEDIUM

References to Advisories, Solutions, and Tools

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/