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.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-g8mr-fgfg-5qpc Koa Vulnerable to Open Redirect via Trailing Double-Slash (//) in back Redirect Logic
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 21 Jan 2026 00:00:00 +0900

Type Values Removed Values Added
CPEs cpe:2.3:a:koajs:koa:*:*:*:*:*:node.js:*:*
cpe:2.3:a:koajs:koa:2.16.2:*:*:*:*:node.js:*:*

Thu, 23 Oct 2025 19:30:00 +0900

Type Values Removed Values Added
First Time appeared Koajs
Koajs koa
Vendors & Products Koajs
Koajs koa

Wed, 22 Oct 2025 09:15:00 +0900

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Wed, 22 Oct 2025 02:15:00 +0900

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 22 Oct 2025 01:30:00 +0900

Type Values Removed Values Added
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.
Title Koa Vulnerable to Open Redirect via Trailing Double-Slash (//) in back Redirect Logic
Weaknesses CWE-601
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-10-21T16:35:48.461Z

Reserved: 2025-10-16T19:24:37.266Z

Link: CVE-2025-62595

cve-icon Vulnrichment

Updated: 2025-10-21T16:35:40.490Z

cve-icon NVD

Status : Analyzed

Published: 2025-10-21T17:15:40.737

Modified: 2026-01-20T14:45:48.283

Link: CVE-2025-62595

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-10-21T16:20:43Z

Links: CVE-2025-62595 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-10-23T19:13:07Z

Weaknesses