CVE-2025-66202
Medium
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.
SeverityMedium
CVSS6.5
Exploit probability—
Product
Astro
PublishedDec 9, 2025
First seenDec 9, 2025
Weakness typeCWE-647CWE-647
How to fix
Update
- astro astro5.15.8 or later
- astro5.15.8 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| astro astro | v < 5.15.8 | 5.15.8 |
| astronpm | v < 5.15.8 | 5.15.8 |
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