CVE-2026-4055

What it is

Mattermost versions 11.5.x <= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-21 08:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-23 16:10 UTC Last updatedMost recent change to the record

Details

Published

2026-05-21 08:16 UTC

Last modified

2026-07-23 16:10 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-863 · Incorrect authorization

Record status

Analyzed

Affected

• Mattermost Server < 10.11.17
• Mattermost Server < 11.5.5
• Mattermost Server < 11.6.2

Attack profile CVSS 3.1 · 4.3

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None