Open Redirect in Koajs Koa
CVE-2025-62595
Koa is expressive middleware for Node.js using ES2017 async functions. In versions 2.16.2 to before 2.16.3 and 3.0.1 to before 3.0.3, a bypass to CVE-2025-8129 was discovered in the Koa.js framework affecting its back redirect functionality. In certain circumstances, an attacker can manipulate the Referer header to force a user’s browser to navigate to an external, potentially malicious website. This occurs because the implementation incorrectly treats some specially crafted URLs as safe relative paths. Exploiting this vulnerability could allow attackers to perform phishing, social engineering, or other redirect-based attacks on users of affected applications. This issue has been patched in version 3.0.3.
Vulnerability class: Open Redirect
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (19.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 19.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
- Koajs Koa — versions >= 2.16.2, < 2.16.3, >= 3.0.1, < 3.0.3, 2.16.2
Weakness classification (CWE)
References
- github.com/koajs/koa/security/advisories/GHSA-g8mr-fgfg-5qpc (Exploit, Vendor Advisory)
- github.com/koajs/koa/commit/769fd75cc6b30d72493b370b5a3ae2332ca03c5b (Patch)
Frequently asked questions
- What is CVE-2025-62595?
- CVE-2025-62595 is a medium-severity vulnerability in Koajs Koa, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 4.3/10. Published 2025-10-21.
- How severe is CVE-2025-62595?
- Medium severity. CVSS v3 base score is 4.3 out of 10.