CVE-2026-12882
Published:September 14, 2026
Updated:September 22, 2026
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
Affected Packages
https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) =v11.9.0 <v11.9.1Fix Suggestion:
Update to version v11.9.1https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v11.8.0 <v11.8.5Fix Suggestion:
Update to version v11.8.5https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v10.11.0 <v10.11.23Fix Suggestion:
Update to version v10.11.23https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v11.7.0 <v11.7.8Fix Suggestion:
Update to version v11.7.8github.com/mattermost/mattermost/server/public (GO):
Affected version(s) >=v0.0.1 <v0.4.4Fix Suggestion:
Update to version v0.4.4Related Resources (2)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Inefficient Algorithmic Complexity
EPSS
Base Score:
0.21