PT-2026-42750 · Mattermost · Mattermost
Zephrfish
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Published
2026-05-22
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Updated
2026-05-22
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CVE-2026-5740
CVSS v3.1
7.5
High
| Vector | AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to properly validate msgpack-encoded WebSocket frames before memory allocation which allows an unauthenticated remote attacker to crash the server process and cause a full service outage for all users via a crafted binary WebSocket message sent to the public WebSocket endpoint.. Mattermost Advisory ID: MMSA-2026-00647
Fix
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Weakness Enumeration
Related Identifiers
Affected Products
Mattermost