CVE-2026-2454
MEDIUMCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Lifecycle Timeline
2Description
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
Analysis
Mattermost versions 11.3.0 and earlier, 11.2.2 and earlier, and 10.11.10 and earlier contain an array length handling vulnerability in the calls plugin that allows unauthenticated remote attackers to trigger out-of-memory (OOM) errors and crash the server by sending maliciously crafted msgpack frames over websocket connections. With a CVSS score of 5.8 and network-based attack vector requiring no privileges or user interaction, this denial-of-service vulnerability poses a moderate but easily exploitable availability risk to any exposed Mattermost deployment.
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.
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