---
id: CVE-2025-62595
title: Koa is expressive middleware for Node.js using ES2017 async functions
summary: >-
  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 functional…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-601
vendor: koajs
product: koa
affected:
  - 'koa >= 3.0.1, < 3.0.3'
  - koa = 2.16.2
patched:
  - koa 3.0.3
published: '2025-10-21'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T11:10:00.250'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-62595'
references:
  - url: >-
      https://github.com/koajs/koa/commit/769fd75cc6b30d72493b370b5a3ae2332ca03c5b
    label: security-advisories@github.com
  - url: 'https://github.com/koajs/koa/security/advisories/GHSA-g8mr-fgfg-5qpc'
    label: security-advisories@github.com
  - url: 'https://github.com/koajs/koa/security/advisories/GHSA-g8mr-fgfg-5qpc'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00295
epssPercentile: 0.2033
ingestedAt: '2026-10-08T11:31:27.456Z'
---

## Overview

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.

## Affected

- `koa >= 3.0.1, < 3.0.3`
- `koa = 2.16.2`

## Remediation

Upgrade past the affected range:

- `koa 3.0.3`