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.

Classification

CVE ID: CVE-2025-25200

CVSS Base Severity: CRITICAL

CVSS Base Score: 9.2

CVSS Vector: 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

Affected Products

Vendor: koajs

Product: koa

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 12.85% (scored less or equal to compared to others)

EPSS Date: 2025-03-13 (when was this score calculated)

References

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

Timeline