Vulnerability in Koajs Koa
CVE-2025-25200
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.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.008 (56.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: +0.000
Affected products
- Koajs Koa — versions >= 2.0.0-alpha.1, < 2.15.4, >= 1.0.0, < 1.7.1, < 0.21.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/koajs/koa/security/advisories/GHSA-593f-38f6-jp5m (Vendor Advisory)
- github.com/koajs/koa/commit/5054af6e31ffd451a4151a1fe144cef6e5d0d83c (Patch)
- github.com/koajs/koa/commit/5f294bb1c7c8d9c61904378d250439a321bffd32 (Patch)
- github.com/koajs/koa/commit/93fe903fc966635a991bcf890cfc3427d33a1a08 (Patch)
- github.com/koajs/koa/blob/master/lib/request.js (Product)
- github.com/koajs/koa/blob/master/lib/request.js (Product)
- github.com/koajs/koa/releases/tag/2.15.4 (Release Notes)
Frequently asked questions
- What is CVE-2025-25200?
- CVE-2025-25200 is a high-severity vulnerability in Koajs Koa, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2025-02-12.
- How severe is CVE-2025-25200?
- High severity. CVSS v3 base score is 7.5 out of 10.
- Is CVE-2025-25200 known to be exploited?
- 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.