CVE-2026-4054

published 2026-05-15

CVE-2026-4054: 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…

medium 6.5 CVSS 3.1

AV N AC L PR N UI R S U C N I N A H

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

9 ranges

Vendor	Product	Version range	Fixed in
github.com	mattermost_mattermost-server	>= 0.0.0-20250731163400-5b955468ea1e < 0.0.0-20260414103857-b21ef302025e	0.0.0-20260414103857-b21ef302025e
github.com	mattermost_mattermost-server	>= 11.4.0 < 11.4.4	11.4.4
github.com	mattermost_mattermost-server	>= 11.5.0 < 11.5.2	11.5.2
mattermost	mattermost	10.11.0 – 10.11.13	—
mattermost	mattermost	11.4.0 – 11.4.3	—
mattermost	mattermost	11.5.0 – 11.5.1	—
mattermost	mattermost_server	>= 10.11.0 < 10.11.14	10.11.14
mattermost	mattermost_server	>= 11.4.0 < 11.4.4	11.4.4
mattermost	mattermost_server	>= 11.5.0 < 11.5.2	11.5.2

CWE-754