CVE-2026-5740
Published: May 22, 2026
Modified: May 22, 2026
CVSS v3.1
7.5
Description
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
| Vendor | Product | Versions |
|---|---|---|
Mattermost | Mattermost | affected 11.6.0 - <= 11.6.0affected 11.5.0 - <= 11.5.3affected 11.4.0 - <= 11.4.4affected 10.11.0 - <= 10.11.14unaffected 11.7.0+4 more versions |
Weaknesses (CWE)
CVSS v3.1 Details
CVSS v3.1 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
References
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