CVE-2026-40356

Publication date 28 April 2026

Last updated 6 August 2026

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
krb5	26.04 LTS resolute	Fixed 1.22.1-2ubuntu4.1
	25.10 questing	Ignored end of life, was needs-triage
	24.04 LTS noble	Fixed 1.20.1-6ubuntu2.7
	22.04 LTS jammy	Fixed 1.19.2-2ubuntu0.8
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

mdeslaur

same commit as CVE-2026-40355

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
krb5	Upstream: 2e75f0d

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.9 · Medium

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	5.9 · Medium
Exploitability score	-
Impact score	-

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

References

Related Ubuntu Security Notices (USN)

USN-8585-1
Kerberos vulnerabilities
22 July 2026

Other references

https://www.cve.org/CVERecord?id=CVE-2026-40356