CVE-2026-12882
Medium
Description
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to parse Markdown autolinks with unmatched trailing closing parentheses in linear time, which allows an authenticated user with permission to create posts to cause excessive server CPU consumption and degrade availability for other users via specially crafted post or message attachment content. Mattermost Advisory ID: MMSA-2026-00703
SeverityMedium
CVSS4.3
Exploit probability—
Product
Mattermost Server
PublishedSep 14, 2026
First seenSep 14, 2026
Weakness typeCWE-407CWE-407
How to fix
Update
- mattermost mattermost_server10.11.23, 11.7.8, 11.8.5, 11.9.1 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.11.0 ≤ v < 10.11.23, 11.7.0 ≤ v < 11.7.8, 11.8.0 ≤ v < 11.8.5, 11.9.0 ≤ v < 11.9.1 | 10.11.23, 11.7.8, 11.8.5, 11.9.1 |
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