CVE-2025-47871: Mattermost Playbooks exposes private channel metadata to unauthorized users via run metadata API

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-06-30 · updated 2026-06-17
Weakness: CWE-863

Description

Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly validate channel membership when retrieving playbook run metadata, allowing authenticated users who are playbook members but not channel members to access sensitive information about linked private channels including channel name, display name, and participant count through the run metadata API endpoint.

Affected products

Mattermost: from 9.11.0 before 9.11.16; from 10.5.0 before 10.5.6; from 10.6.0 before 10.6.6; from 10.7.0 before 10.7.3; 10.8.0, 10.8.0-rc1, 10.8.0-rc2, 10.8.0-rc3 — fixed in 10.5.6, 10.6.6, 10.7.3, 9.11.16

How to fix

Upgrade to a fixed version: Mattermost 10.5.6, 10.6.6, 10.7.3, 9.11.16. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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