Is CVE-2026-40356 actively exploited?

No active exploitation of CVE-2026-40356 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-40356 be exploited remotely?

Yes. CVE-2026-40356 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-40356?

CVE-2026-40356 has a CVSS score of 5.9 (MEDIUM).

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MEDIUM

CVE-2026-40356

CWE-191Published: April 28, 2026· Updated: Apr 28, 2026

5.9

CVSS v3.1

EPSS:0.07%probability of exploitation in 30 daysPercentile:22.4th

Official 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.

NVD Source

Technical Analysis

CVE-2026-40356 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 5.9.