Mattermost API Input Validation flaw (v10.1111.6) causes plugin crash
CVE-2026-4646 Published on May 22, 2026

Insufficient input validation in GitHub plugin API causes denial of service
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate user-supplied input in API request handlers which allows an authenticated attacker to crash the plugin process via a crafted HTTP request to the PR details endpoint.. Mattermost Advisory ID: MMSA-2026-00638

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-4646 is exploitable 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 and integrity, and a small impact on availability.

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

Weakness Type

Improper Validation of Specified Type of Input

The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.


Products Associated with CVE-2026-4646

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MatterMost
 

Affected Versions

Mattermost: