Mattermost v10.11.13 & v11.5.1: Authenticated Post Edit Spoofing
CVE-2026-3637 Published on May 18, 2026

Mattermost fails to enforce create_post permission when editing posts
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to check the create_post channel permission during post edit operations which allows an authenticated attacker with revoked posting privileges to modify their existing posts via direct API requests to the post update and patch endpoints.. Mattermost Advisory ID: MMSA-2026-00627

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-3637 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
LOW
Availability Impact:
NONE

Weakness Type

What is an AuthZ Vulnerability?

The software does not perform an authorization check when an actor attempts to access a resource or perform an action.

CVE-2026-3637 has been classified to as an AuthZ vulnerability or weakness.


Products Associated with CVE-2026-3637

Want to know whenever a new CVE is published for MatterMost? stack.watch will email you.

MatterMost
 

Affected Versions

Mattermost: