4.3

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-6343

CVE-2026-6343: Mattermost doesn't check public/private permissions

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to check public/private permissions which allows members without these permissions to access public playbooks via /get.. Mattermost Advisory ID: MMSA-2026-00591

(GitHub Advisory)

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CVE-2026-6343

CVE-2026-6343:

4.3

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
github.com/mattermost/mattermost/server/v8	go	>= 11.5.0, < 11.5.2	11.5.2
github.com/mattermost/mattermost/server/v8	go	>= 11.4.0, < 11.4.4	11.4.4
github.com/mattermost/mattermost/server/v8	go	>= 10.11.0, < 10.11.14	10.11.14
github.com/mattermost/mattermost-plugin-playbooks	go	< 1.41.1-0.20260309184833-887d9cacb616	1.41.1-0.20260309184833-887d9cacb616

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in Mattermost Playbooks' failure to consistently check for view permissions across various API endpoints and application commands that list or interact with playbooks. Several functions responsible for retrieving lists of playbooks for different features (e.g., the main playbook list, autocomplete suggestions, GraphQL queries, and slash commands) did not filter the results based on the user's permissions. This allowed any authenticated user, regardless of their role or team membership, to discover the existence and names of all public playbooks on the Mattermost instance. The security patch addresses this by introducing a new centralized function, FilterPlaybooksByViewPermission, which is now called by all the affected functions to ensure that only playbooks a user is authorized to see are returned. This comprehensive fix ensures that the permission model is enforced consistently across the application.

Vulnerable functions

PlaybookHandler.getPlaybooks

server/api/playbooks.go

This function, which handles API requests to list playbooks, did not filter the returned playbooks based on the user's view permissions. This allowed any authenticated user to see all public playbooks, regardless of their permissions. The patch introduces a call to `FilterPlaybooksByViewPermission` to correctly filter the list.

PlaybookHandler.getPlaybooksAutoComplete

server/api/playbooks.go

This function, providing playbooks for autocomplete suggestions, returned all playbooks without checking for view permissions. An attacker could use the autocomplete feature to discover the existence and names of playbooks they are not authorized to see. The patch filters the playbooks using `FilterPlaybooksByViewPermission`.

CategoryHandler.getPlaybooksCategory

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WAF Protection Rules

WAF Rule

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Reasoning

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