What is CVE-2026-40356?

CVE-2026-40356 is a medium-severity vulnerability in Mit Kerberos 5, classified under Integer Underflow. CVSS score: 5.9/10. Published 2026-04-28.

How severe is CVE-2026-40356?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Integer overflow in Mit Kerberos 5

CVE-2026-40356

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…

EPSS: 0.001 (28.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Mit Kerberos 5 — versions 1.18

Weakness classification (CWE)

CWE-191 — Integer Underflow

References

cve@mitre.org
cve@mitre.org
cve@mitre.org

Frequently asked questions

What is CVE-2026-40356?: CVE-2026-40356 is a medium-severity vulnerability in Mit Kerberos 5, classified under Integer Underflow. CVSS score: 5.9/10. Published 2026-04-28.
How severe is CVE-2026-40356?: Medium severity. CVSS v3 base score is 5.9 out of 10.