CVE-2025-25200
highpriority · track · 40EPSS 0.008 · 58 %ileexploit · PoCEUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 7.5–9.2
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
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exploits (2)
Public proof-of-concept and weaponised exploit code.
affected products (12)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-593f-38f6-jp5mInefficient Regular Expression Complexity in koa2025-02-12ghsa · osvUS
### 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.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (21)
External citations — patches, advisories, analysis.
- https://github.com/koajs/koa/blob/master/lib/request.js#L259cnnvd
- https://github.com/koajs/koa/blob/master/lib/request.js#L404cnnvd
- https://github.com/koajs/koa/commit/5054af6e31ffd451a4151a1fe144cef6e5d0d83ccnnvd
- https://github.com/koajs/koa/commit/5f294bb1c7c8d9c61904378d250439a321bffd32cnnvd
- https://github.com/koajs/koa/commit/93fe903fc966635a991bcf890cfc3427d33a1a08cnnvd
- https://github.com/koajs/koa/releases/tag/2.15.4cnnvd
- https://github.com/koajs/koa/security/advisories/GHSA-593f-38f6-jp5mcnnvd
- https://github.com/koajs/koa/blob/master/lib/request.js#L259enisa_euvd
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