Mattermost Inadequate Channel Access Validation in Board Linking 10.11-11.8
CVE-2026-16047 Published on August 17, 2026

Board channel linking without read channel permission validation
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-16047 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 a small impact on confidentiality, a small impact on integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
NONE
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-2026-16047 has been classified to as an AuthZ vulnerability or weakness.


Products Associated with CVE-2026-16047

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Affected Versions

Mattermost: