Inefficient Regular Expression Complexity in koa
### Summary 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. ### PoC Coming soon. ### Impact This is a Regex Denial-of-Service attack and causes memory exhaustion. The regex should be improved and empty values should not be allowed.
01
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2025-25200US | high7.5 | Exploit | ||
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-… | ||||
02
references
External citations — patches, advisories, analysis.
- https://github.com/koajs/koaPACKAGE
- https://github.com/koajs/koa/commit/5054af6e31ffd451a4151a1fe144cef6e5d0d83cWEB
- https://github.com/koajs/koa/commit/5f294bb1c7c8d9c61904378d250439a321bffd32WEB
- https://github.com/koajs/koa/commit/93fe903fc966635a991bcf890cfc3427d33a1a08WEB
- https://github.com/koajs/koa/releases/tag/2.15.4WEB
- https://github.com/koajs/koa/security/advisories/GHSA-593f-38f6-jp5mWEB
- https://nvd.nist.gov/vuln/detail/CVE-2025-25200ADVISORY
scry
Advisories like this name the exposed products attackers go after on your perimeter. See what is exposed on your perimeter with a free passive scan.
Free scan