CVE-2026-4054
Fixed in a distro release EPSS <1%CVSS 4.3
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
Products: Mattermost
Fixed upstream
| Ecosystem | Package | Fixed in |
|---|---|---|
| Go | github.com/mattermost/mattermost-server | 11.5.2 |
| Go | github.com/mattermost/mattermost-server | 0.0.0-20260414103857-b21ef302025e |
| Go | github.com/mattermost/mattermost-server | 11.4.4 |
| Go | github.com/mattermost/mattermost-server | 11.4.4+incompatible |
| Go | github.com/mattermost/mattermost-server | 11.5.2+incompatible |
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| openSUSE:Leap 16.0 | govulncheck-vulndb | 0.0.20260723T184607-160000.1.1 |