CVE-2026-2454 PUBLISHED

DoS in Calls plugin via malformed msgpack in websocket request.

Assigner: Mattermost
Reserved: 13.02.2026 Published: 16.03.2026 Updated: 17.03.2026

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

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
CVSS Score: 5.8

Attack Vector	Network	Scope	Changed
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.3.0 to 11.3.0 (incl.) affected from 11.2.0 to 11.2.2 (incl.) affected from 10.11.0 to 10.11.10 (incl.) Version 11.4.0 is unaffected Version 11.3.1 is unaffected Version 11.2.3 is unaffected Version 10.11.11 is unaffected

Solutions

Update Mattermost to versions 11.4.0, 11.3.1, 11.2.3, 10.11.11 or higher.

Credits

National Security Agency finder

References

MMSA-2025-00537

Problem Types

CWE-1287: Improper Validation of Specified Type of Input CWE