CVE-2026-3472

Markdown image rendering bypass in AI bot tool result posts in Mattermost

Published Jun 26, 2026 CVSS 3.1 · 3.5 Low EPSS < 1% KEV · Not listed
Description
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

Remediation

Vendor Solution

Update Mattermost to versions 11.7.0, 10.11.19, 11.6.4, 11.5.7 or higher.

Tracking

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Advisories

No advisories available
References
History
Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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
Title Markdown image rendering bypass in AI bot tool result posts in Mattermost
Weaknesses CWE-693
References
Metrics cvssV3_1

{'score': 3.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Jun 26, 2026, 3:41 PM
Reserved
Mar 3, 2026, 11:25 AM
Status
Analyzed
Published
Jun 26, 2026, 3:16 PM
Modified
Jun 29, 2026, 7:27 PM