CVE-2025-25200: 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.
Published Feb 12, 2025
Affected packages
koa
- Ecosystem
- npm
- Affected
- >= 2.0.0, < 2.15.4
- Fixed in
- 2.15.4
- Check
npm ls koa
koa
- Ecosystem
- npm
- Affected
- >= 3.0.0-alpha.0, < 3.0.0-alpha.3
- Fixed in
- 3.0.0-alpha.3
- Check
npm ls koa
koa
- Ecosystem
- npm
- Affected
- >= 1.0.0, < 1.7.1
- Fixed in
- 1.7.1
- Check
npm ls koa
koa
- Ecosystem
- npm
- Affected
- < 0.21.2
- Fixed in
- 0.21.2
- Check
npm ls koa
Advisory details
From the GitHub Advisory Database (CC BY 4.0).
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.
Credited to R4356th.
References
- https://github.com/koajs/koa/security/advisories/GHSA-593f-38f6-jp5m
- https://nvd.nist.gov/vuln/detail/CVE-2025-25200
- 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/releases/tag/2.15.4
- https://github.com/advisories/GHSA-593f-38f6-jp5m
How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology