# CVE-2025-21088

## Summary

- **CVE ID:** CVE-2025-21088
- **Severity:** MEDIUM
- **CVSS Score:** 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** CWE-704
- **Published:** Jan 15, 2025
- **Last Modified:** Mar 12, 2026

## Description

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.

## Affected Products

- Mattermost — Mattermost (10.2.0)
- Mattermost — Mattermost (9.11.0)
- Mattermost — Mattermost (10.0.0)
- Mattermost — Mattermost (10.1.0)
- Mattermost — Mattermost (10.3.0)
- Mattermost — Mattermost (10.2.1)
- Mattermost — Mattermost (9.11.6)
- Mattermost — Mattermost (10.0.4)
- Mattermost — Mattermost (10.1.4)

## References

- [CNA](https://mattermost.com/security-updates)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.56%
- **EPSS Percentile:** 44.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._