CVE-2026-2454

DoS in Calls plugin via malformed msgpack in websocket request.

CVSS 5.8 MEDIUMEPSS 0.3%CWE-1287

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 5.8EPSS 0.3%KEV nãoPoC —Nuclei —Metasploit —Patch referenciado

Lifecycle

16 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Affected products

Mattermost · Mattermost

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References

https://mattermost.com/security-updates