What is GHSA-j76w-p754-g2w7?

GHSA-j76w-p754-g2w7 is a security advisory published by GitHub Security Advisories with Medium severity. Mattermost doesn't validate the response body of proxied images

Which CVE IDs does GHSA-j76w-p754-g2w7 cover?

GHSA-j76w-p754-g2w7 covers the following CVE IDs: CVE-2026-4054. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of GHSA-j76w-p754-g2w7?

GHSA-j76w-p754-g2w7 has a CVSS v3 base score of 4.3, published by GitHub Security Advisories.

Which products are affected by GHSA-j76w-p754-g2w7?

GHSA-j76w-p754-g2w7 affects 3 products, including: go/github.com/mattermost/mattermost-server:\u003e= 11.5.0, \u003c 11.5.2; go/github.com/mattermost/mattermost-server:\u003e= 0.0.0-20250731163400-5b955468ea1e, \u003c 0.0.0-20260414103857-b21ef302025e; go/github.com/mattermost/mattermost-server:\u003e= 11.4.0, \u003c 11.4.4.

GHSA-j76w-p754-g2w7MediumCVSS 4.3

Mattermost doesn't validate the response body of proxied images

Vendor

GitHub Security Advisories

Published

May 15, 2026

Last Modified

May 28, 2026

🔗 CVE IDs covered (1)

CVE-2026-4054 →

📋 Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate the response body of proxied images, which allows a remote attacker to enact client-side DoS via an SVG file served from an attacker-controlled origin under a non-SVG Content-Type header (e.g. image/png) embedded in an og:image meta tag or Markdown image link. Mattermost Advisory ID: MMSA-2026-00630.

🎯 Affected products3

go/github.com/mattermost/mattermost-server:>= 11.5.0, < 11.5.2
go/github.com/mattermost/mattermost-server:>= 0.0.0-20250731163400-5b955468ea1e, < 0.0.0-20260414103857-b21ef302025e
go/github.com/mattermost/mattermost-server:>= 11.4.0, < 11.4.4

🔗 References (3)

https://nvd.nist.gov/vuln/detail/CVE-2026-4054
https://mattermost.com/security-updates
https://github.com/advisories/GHSA-j76w-p754-g2w7