CVE-2026-2454

Medium

Description

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

SeverityMedium

CVSS5.8

Exploit probability—

Product

Mattermost Server

PublishedMar 16, 2026

First seenMar 16, 2026

Weakness typeCWE-1287CWE-1287

How to fix

Update

mattermost mattermost_server10.11.11, 11.2.3, 11.3.1 or later

Vendor advisories

mattermost.com/security-updates

Affected products

Product	Affected versions	Fixed in
mattermost mattermost_server	10.11.0 ≤ v < 10.11.11, 11.2.0 ≤ v < 11.2.3, 11.3.0 ≤ v < 11.3.1	10.11.11, 11.2.3, 11.3.1

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