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…

PriorityP417low3.5CVSS 3.1

AVNACLPRLUIRSUCLINAN

EPSS

0.19%

9.3th percentile

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

Affected

6 ranges

Vendor	Product	Version range	Fixed in
mattermost	mattermost	10.11.0 – 10.11.18	—
mattermost	mattermost	11.5.0 – 11.5.6	—
mattermost	mattermost	11.6.0 – 11.6.3	—
mattermost	mattermost_server	>= 10.11.0 < 10.11.19	10.11.19
mattermost	mattermost_server	>= 11.5.0 < 11.5.7	11.5.7
mattermost	mattermost_server	>= 11.6.0 < 11.6.4	11.6.4

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