CVE-2026-6673

Published: Jun 22, 2026Modified: Jun 23, 2026

6.4

Vector

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

Exploitability: 1.2 / Impact: 5.2

Source: responsibledisclosure@mattermost.com (Secondary)

Description

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

Affected (4)

Products: Mattermost: Mattermost Server

Mattermost

1 product

Mattermost Server

Configuration A

4 vulnerable

Vulnerable Software	Affected Versions
Mattermost Mattermost Server	From 10.11.0 to 10.11.18
Mattermost Mattermost Server	From 11.5.0 to 11.5.6
Mattermost Mattermost Server	From 11.6.0 to 11.6.3
Mattermost Mattermost Server	From 11.7.0 to 11.7.1

Related CWEs

CWE-306

Missing Authentication for Critical Function

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

References (1)

https://mattermost.com/security-updates

Source: responsibledisclosure@mattermost.com

Vendor Advisory

Timeline

No history available yet.