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-...

Description

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.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.28%

19.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-601

Affected Software

Vendor	Product	Versions
Koajs	Koa	>= 3.0.1, < 3.0.3
Koajs	Koa	2.16.2

References

https://github.com/koajs/koa/commit/769fd75cc6b30d72493b370b5a3ae2332ca03c5bPatch
https://github.com/koajs/koa/security/advisories/GHSA-g8mr-fgfg-5qpcExploit, Vendor Advisory
https://github.com/koajs/koa/security/advisories/GHSA-g8mr-fgfg-5qpcExploit, Vendor Advisory

Timeline

Published: Oct 21, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is 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.

How severe is CVE-2025-62595?

CVE-2025-62595 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.28% probability of exploitation in the next 30 days.

How do I fix CVE-2025-62595?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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