# CVE-2025-25200

## Summary

- **CVE ID:** CVE-2025-25200
- **Severity:** CRITICAL
- **CVSS Score:** 9.2 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H)
- **CWE:** CWE-1333
- **Published:** Feb 12, 2025
- **Last Modified:** Mar 12, 2026

## Description

Koa is expressive middleware for Node.js using ES2017 async functions. Prior to versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3, Koa uses an evil regex to parse the `X-Forwarded-Proto` and `X-Forwarded-Host` HTTP headers. This can be exploited to carry out a Denial-of-Service attack. Versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3 fix the issue.

## Affected Products

- koajs — koa (< 0.21.2)
- koajs — koa (>= 1.0.0, < 1.7.1)
- koajs — koa (>= 2.0.0-alpha.1, < 2.15.4)
- koajs — koa (>= 3.0.0-alpha.0, < < 3.0.0-alpha.3)

## References

- [CNA](https://github.com/koajs/koa/security/advisories/GHSA-593f-38f6-jp5m)
- [CNA](https://github.com/koajs/koa/commit/5054af6e31ffd451a4151a1fe144cef6e5d0d83c)
- [CNA](https://github.com/koajs/koa/commit/5f294bb1c7c8d9c61904378d250439a321bffd32)
- [CNA](https://github.com/koajs/koa/commit/93fe903fc966635a991bcf890cfc3427d33a1a08)
- [CNA](https://github.com/koajs/koa/blob/master/lib/request.js#L259)
- [CNA](https://github.com/koajs/koa/blob/master/lib/request.js#L404)
- [CNA](https://github.com/koajs/koa/releases/tag/2.15.4)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.84%
- **EPSS Percentile:** 55.8

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