CVE-2026-26230
Permission Validation Bypass in Mattermost Team Roles API
Publication date: 2026-03-16
Last updated on: 2026-03-18
Assigner: Mattermost, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mattermost | mattermost_server | From 10.11.0 (inc) to 10.11.11 (exc) |
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 exists in Mattermost versions 10.11.x up to and including 10.11.10. It occurs because the software fails to properly validate permission requirements in the team member roles API endpoint. This flaw allows team administrators to demote members to the guest role, which they might not be authorized to do.
How can this vulnerability impact me? :
The impact of this vulnerability is that team administrators could improperly change the roles of team members by demoting them to guest status. This could lead to unauthorized restriction of access or privileges for certain users within a Mattermost team, potentially disrupting collaboration or access to information.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
I don't know