CVEvulnerability

CVE-2026-5740

7.5 HIGH Published 2026-05-22 Modified 2026-07-23 Official page ↗
Status
Analyzed
Published
2026-05-22
Last modified
2026-07-23
Assigner
[email protected]
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-789

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

Affected configurations

• mattermost mattermost server (>= 10.11.0 < 10.11.15) • mattermost mattermost server (>= 11.4.0 < 11.4.5) • mattermost mattermost server (>= 11.5.0 < 11.5.4) • mattermost mattermost server (>= 11.6.0 < 11.6.1)

Related

Weakness · CWE (1)

  • CWE-789 Memory Allocation with Excessive Size Value weakness

References