CVE-2026-5740

CVSS Score & Metrics

Base Score

7.5 / 10

Vector String

                                        CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H                                    

Vulnerability 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

Vulnerability Details

Published Date

May 22, 2026

Last Modified

May 22, 2026

CWE ID

CWE-789

Source

NVD

Vendor

mattermost

Product

mattermost_server

External References

https://mattermost.com/security-updates

CVSS Score & Metrics

Vulnerability Description

Vulnerability Details

External References

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