# CVE-2021-39173

## Summary

- **CVE ID:** CVE-2021-39173
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-704
- **Published:** Aug 27, 2021
- **Last Modified:** Mar 13, 2026

## Description

Cachet is an open source status page system. Prior to version 2.5.1 authenticated users, regardless of their privileges (User or Admin), can trick Cachet and install the instance again, leading to arbitrary code execution on the server. This issue was addressed in version 2.5.1 by improving the middleware `ReadyForUse`, which now performs a stricter validation of the instance name. As a workaround, only allow trusted source IP addresses to access to the administration dashboard.

## Affected Products

- fiveai — Cachet (< 2.5.1)

## References

- [CNA](https://github.com/fiveai/Cachet/releases/tag/v2.5.1)
- [CNA](https://github.com/fiveai/Cachet/security/advisories/GHSA-r67m-m8c7-jp83)
- [CNA](https://blog.sonarsource.com/cachet-code-execution-via-laravel-configuration-injection/)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 2.88%
- **EPSS Percentile:** 86.0

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