CVE-2026-9708

Published: Jul 13, 2026Modified: Jul 13, 2026

4.9

Vector

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

Exploitability: 1.2 / Impact: 3.6

Source: responsibledisclosure@mattermost.com (Secondary)

Description

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683

Affected (3)

Products: Mattermost: Mattermost Server

Mattermost

1 product

Mattermost Server

Configuration A

3 vulnerable

Vulnerable Software	Affected Versions
Mattermost Mattermost Server	From 10.11.0 to 10.11.20
Mattermost Mattermost Server	From 11.6.0 to 11.6.5
Mattermost Mattermost Server	From 11.7.0 to 11.7.3

Related CWEs

CWE-639

Authorization Bypass Through User-Controlled Key

The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

References (1)

https://mattermost.com/security-updates

Source: responsibledisclosure@mattermost.com

Vendor Advisory

Timeline

No history available yet.