SVG content served through Mattermost image proxy despite Content-Type restrictions causes client-side denial of service
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 11.5.2, 0.0.0-20260414103857-b21ef302025e, 11.4.4, 11.4.4+incompatible, 11.5.2+incompatible
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
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
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- Mattermost Mattermost
From 11.5.0 · through 11.5.1; From 10.11.0 · through 10.11.13; From 11.4.0 · through 11.4.3
- github.com/mattermost/mattermost-serverGo
From 11.5.0 · fixed in 11.5.2
- github.com/mattermost/mattermost-serverGo
From 0.0.0-20250731163400-5b955468ea1e · fixed in 0.0.0-20260414103857-b21ef302025e
- github.com/mattermost/mattermost-serverGo
From 11.4.0 · fixed in 11.4.4
- github.com/mattermost/mattermost-serverGo
From 0.0.0-20250731163400-5b955468ea1e · fixed in 0.0.0-20260414103857-b21ef302025e; From 11.4.0+incompatible · fixed in 11.4.4+incompatible; From 11.5.0+incompatible · fixed in 11.5.2+incompatible