CVE-2026-40356

MEDIUM

MIT Kerberos 5 1.18-<1.22.3 - Unauthenticated Integer Underflow via NegoEx Mechanism

Title source: llm

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.

References (3)

Core 3

Core 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

View Patch ZIP pw:eip

Scores

CVSS v3 5.9

EPSS 0.0060

EPSS Percentile 45.5%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-191

Status published

Products (2)

MIT/Kerberos 5 1.18 - 1.22.3

mit/kerberos_5 1.18.0 - 1.22.2

Published Apr 28, 2026

Tracked Since Apr 28, 2026