Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly validate the style of proto supplied to an action's style in post.props.attachments, which allows an attacker to crash the frontend via crafted malicious input.
CVE ID: CVE-2025-21088
CVSS Base Severity: MEDIUM
CVSS Base Score: 6.5
Vendor: Mattermost
Product: Mattermost
EPSS Score: 0.04% (probability of being exploited)
EPSS Percentile: 11.5% (scored less or equal to compared to others)
EPSS Date: 2025-02-13 (when was this score calculated)