CVE-2026-6342
Subscription Bypass in Mattermost Plugins
Publication date: 2026-05-18
Last updated on: 2026-05-18
Assigner: Mattermost, Inc.
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mattermost | plugins | to 11.5 (inc) |
| mattermost | plugins | 11.1.5 |
| mattermost | plugins | 10.13.11 |
| mattermost | plugins | 11.3.4.0 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-863 | The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability affects Mattermost Plugins versions up to 11.5, including versions 11.1.5, 10.13.11, and 11.3.4.0. The issue is that these versions fail to properly verify valid namespaces when creating group subscriptions. Specifically, plugin users can create subscriptions to groups that were not whitelisted by exploiting the ability to create groups with the same prefix as a whitelisted group.
How can this vulnerability impact me? :
The vulnerability allows plugin users to bypass namespace restrictions and subscribe to unauthorized groups by creating groups with prefixes matching whitelisted groups. This can lead to unauthorized access or interaction with groups that should be restricted, potentially compromising the intended access controls within the Mattermost environment.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade Mattermost Plugins to versions later than 11.5, 11.1.5, 10.13.11, or 11.3.4.0, as these versions fail to properly check for valid namespaces allowing unauthorized group subscriptions.
Stay informed about security updates and patches by regularly checking Mattermost's official security updates page and subscribing to their Security Bulletin.