CVE-2026-3472CWE-693

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

Low · published June 26, 2026

CVSS v3.1
3.5
EPSS
0%
Percentile
18.3
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
3.5 · LOW
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00271 · 18.3th percentile
Weakness
CWE-693 · Protection Mechanism Failure
Published
2026-06-26T14:42Z
EPSS history
Timeline
  • 26 JUN 14:42Z
    Markdown image rendering bypass in AI bot tool result posts in Mattermost
    cvelistv5