CVE-2025-66202: Astro

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

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 products

• Astro Astro: before 5.15.8 (fixed in 5.15.8)

Published 2025-12-09. Last modified 2026-10-07.