CVE-2025-41395: Webapp DoS via malicious retrospective post in Playbooks

Severity: high (CVSS 7.5 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: 2025-04-24 · updated 2026-06-17
Weakness: CWE-1287

Description

Mattermost versions 10.4.x <= 10.4.2, 10.5.x <= 10.5.0, 9.11.x <= 9.11.10 fail to properly validate the props used by the RetrospectivePost custom post type in the Playbooks plugin, which allows an attacker to create a specially crafted post with maliciously crafted props and cause a denial of service (DoS) of the web app for all users.

Affected products

Mattermost: from 9.11.0 before 9.11.11; from 10.4.0 before 10.4.3; from 10.5.0 before 10.5.1 — fixed in 10.4.3, 10.5.1, 9.11.11

How to fix

Upgrade to a fixed version: Mattermost 10.4.3, 10.5.1, 9.11.11. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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