What is GHSA-mg83-f953-3vq5?

GHSA-mg83-f953-3vq5 is a security advisory published by GitHub Security Advisories with Medium severity. Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign...

Which CVE IDs does GHSA-mg83-f953-3vq5 cover?

GHSA-mg83-f953-3vq5 covers the following CVE IDs: CVE-2026-15754. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of GHSA-mg83-f953-3vq5?

GHSA-mg83-f953-3vq5 has a CVSS v3 base score of 4.2, published by GitHub Security Advisories.

GHSA-mg83-f953-3vq5MediumCVSS 4.2

Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign...

Vendor

GitHub Security Advisories

Published

August 17, 2026

Last Modified

August 17, 2026

🔗 CVE IDs covered (1)

CVE-2026-15754 →

📋 Description

Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718

🔗 References (3)

https://nvd.nist.gov/vuln/detail/CVE-2026-15754
https://mattermost.com/security-updates
https://github.com/advisories/GHSA-mg83-f953-3vq5