# CVE-2026-9812

## Summary

- **CVE ID:** CVE-2026-9812
- **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-639
- **Published:** Sep 14, 2026
- **Last Modified:** Sep 14, 2026

## Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate that a property field belongs to the specified run before updating its value which allows an authenticated user with run property-management access to crash the Playbooks plugin via a REST request referencing a property field that belongs to a different run. Mattermost Advisory ID: MMSA-2026-00684

## Affected Products

- Mattermost — Mattermost (11.9.0)
- Mattermost — Mattermost (11.8.0)
- Mattermost — Mattermost (11.7.0)
- Mattermost — Mattermost (10.11.0)
- Mattermost — Mattermost (11.10.0)
- Mattermost — Mattermost (11.9.1)
- Mattermost — Mattermost (11.8.5)
- Mattermost — Mattermost (11.7.8)
- Mattermost — Mattermost (10.11.23)

## References

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

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.21%
- **EPSS Percentile:** 11.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._