What is CVE-2026-2454?

CVE-2026-2454 is a medium-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 5.8/10. Published 2026-03-16.

How severe is CVE-2026-2454?

Medium severity. CVSS v3 base score is 5.8 out of 10.

Vulnerability in Mattermost

CVE-2026-2454

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to handle incorrectly reported array lengths which allows malicious user to cause OOM errors and crash the server via sending corrupted msgpack frames within websocket messages to calls plugin. Mattermost Advisory ID: MMSA-2025-00537

EPSS: 0.003 (19.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L.

Affected products

Mattermost — versions 11.3.0, 11.2.0, 10.11.0
Mattermost Mattermost_server

Weakness classification (CWE)

CWE-1287

References

responsibledisclosure@mattermost.com (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-2454?: CVE-2026-2454 is a medium-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 5.8/10. Published 2026-03-16.
How severe is CVE-2026-2454?: Medium severity. CVSS v3 base score is 5.8 out of 10.