CVE-2025-36530: Import Path Traversal Enables Unauthorized Unsigned Plugin Installation

Severity: medium (CVSS 4.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-21 · updated 2026-06-17
Weakness: CWE-22

Description

Mattermost versions 10.9.x <= 10.9.1, 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate file paths during plugin import operations which allows restricted admin users to install unauthorized custom plugins via path traversal in the import functionality, bypassing plugin signature enforcement and marketplace restrictions.

Affected products

Mattermost: from 9.11.0 before 9.11.18; from 10.5.0 before 10.5.9; from 10.8.0 before 10.8.4; from 10.9.0 before 10.9.2 — fixed in 10.5.9, 10.8.4, 10.9.2, 9.11.18

How to fix

Upgrade to a fixed version: Mattermost 10.5.9, 10.8.4, 10.9.2, 9.11.18. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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