Bug 2448240 (CVE-2026-2454)

Summary: CVE-2026-2454 github.com/mattermost/mattermost-server/: DoS in Calls plugin via malformed msgpack in websocket request.
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A denial of service flaw has been discovered in mattermost server. Affected versions 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.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2448272, 2448273    
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Description OSIDB Bzimport 2026-03-16 21:03:13 UTC
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