---
id: CVE-2025-66202
title: Astro is a web framework
summary: >-
  Astro is a web framework. Versions 5.15.7 and below have a double URL encoding
  bypass which allows any unauthenticated attacker to bypass path-based
  authentication checks in Astro middleware, granting unauthorized access to
  protected rou…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-647
vendor: astro
product: astro
affected:
  - astro < 5.15.8
patched:
  - astro 5.15.8
published: '2025-12-09'
updated: '2026-10-07'
sourceUpdated: '2026-10-07T20:10:01.970'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-66202'
references:
  - url: >-
      https://github.com/withastro/astro/commit/6f800813516b07bbe12c666a92937525fddb58ce
    label: security-advisories@github.com
  - url: 'https://github.com/withastro/astro/security/advisories/GHSA-ggxq-hp9w-j794'
    label: security-advisories@github.com
  - url: 'https://github.com/withastro/astro/security/advisories/GHSA-whqg-ppgf-wp8c'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00314
epssPercentile: 0.22183
ingestedAt: '2026-10-07T20:46:46.779Z'
---

## Overview

Astro is a web framework. Versions 5.15.7 and below have a double URL encoding bypass which allows any unauthenticated attacker to bypass path-based authentication checks in Astro middleware, granting unauthorized access to protected routes. While the original CVE-2025-64765 was fixed in v5.15.8, the fix is insufficient as it only decodes once. By using double-encoded URLs, attackers can still bypass authentication and access any route protected by middleware pathname checks. This issue is fixed in version 5.15.8.

## Affected

- `astro < 5.15.8`

## Remediation

Upgrade past the affected range:

- `astro 5.15.8`