CVE-2025-66202

Astro has an Authentication Bypass via Double URL Encoding, a bypass for CVE-2025-64765

Published Dec 8, 2025 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-whqg-ppgf-wp8c Astro has an Authentication Bypass via Double URL Encoding, a bypass for CVE-2025-64765
History
Type Values Removed Values Added
First Time appeared Astro
Astro astro
CPEs cpe:2.3:a:astro:astro:*:*:*:*:*:node.js:*:*
Vendors & Products Astro
Astro astro
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Withastro
Withastro astro
Vendors & Products Withastro
Withastro astro
Type Values Removed Values Added
Description 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.
Title Astro has an Authentication Bypass via Double URL Encoding, a bypass for CVE-2025-64765
Weaknesses CWE-647
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Dec 9, 2025, 4:04 PM
Reserved
Nov 24, 2025, 11:01 PM
Status
Analyzed
Published
Dec 9, 2025, 12:15 AM
Modified
Oct 7, 2026, 8:10 PM