CVE-2026-3472: Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows a
Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows an authenticated attacker to exfiltrate data to an attacker-controlled server via injecting markdown image syntax into tool result content rendered by a victim's client.. Mattermost Advisory ID: MMSA-2026-00619
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-3472
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-34720.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-3472 | coverage & exploitation status | NVD · CVE.org |
Recent advisories for Mattermost
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- mediumGHSA-4m3v-q747-pc6h: OpenClaw: Mattermost slash token revocation could lag until monitor refreshghsa · 2026-07-02
- mediumGHSA-gp79-m99v-gjmh: OpenClaw: Mattermost handlers could fall open when channel type was missingghsa · 2026-07-02
- unknownMultiple vulnerabilities in Mattermost Server (June 29, 2026)cert-fr-avis · 2026-06-29
- mediumCVE-2026-9699: Mattermost Plugins versions <=11.6 10.18.11 11.3.6 11.6.5.0 fail to sanitize error responses fr…nvd · 2026-06-26
- mediumCVE-2026-4339: Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to validate at…nvd · 2026-06-26
- mediumCVE-2026-13426: The Mattermost Go module github.com/mattermost/mattermost/server/public versions < v0.1.22 fai…nvd · 2026-06-26
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