Vulnerability in Mattermost
CVE-2025-20621
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 handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the webapp to cr…
EPSS: 0.004 (35.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Mattermost — versions 10.2.0, 9.11.0, 10.0.0
- Mattermost Mattermost_server — versions 10.2.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- responsibledisclosure@mattermost.com (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-20621?
- CVE-2025-20621 is a medium-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 6.5/10. Published 2025-01-16.
- How severe is CVE-2025-20621?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2025-20621 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.