CVE-2026-95666

Published: Sep 22, 2026Modified: Oct 7, 2026

4.3

Vector

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

Exploitability: 2.8 / Impact: 1.4

Source: responsibledisclosure@mattermost.com (Secondary)

Description

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive database load via a crafted request to {{POST /api/v4/posts/ids/reactions}}.. Mattermost Advisory ID: MMSA-2026-00771

Affected (4)

Products: Mattermost: Mattermost Server

Mattermost

1 product

Mattermost Server

Configuration A

4 vulnerable

Vulnerable Software	Affected Versions
Mattermost Mattermost Server	11.10.0 ≤ version < 11.10.2
Mattermost Mattermost Server	11.7.0 ≤ version < 11.7.11
Mattermost Mattermost Server	11.8.0 ≤ version < 11.8.6
Mattermost Mattermost Server	11.9.0 ≤ version < 11.9.2

Related CWEs

CWE-770

Allocation of Resources Without Limits or Throttling

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

References (1)

https://mattermost.com/security-updates

Source: responsibledisclosure@mattermost.com

Vendor Advisory

Timeline

No history available yet.