Vulnerability · Published Dec 8, 2025 · Assigned by GitHub_M
CVE-2025-66202Astro has an Authentication Bypass via Double URL Encoding, a bypass for CVE-2025-64765
Medium 6.5
In plain English
A medium-severity security flaw in astro from withastro. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | astro | 5.15.8 | GHSA-whqg-ppgf-wp8c |
Affected products (as reported)
Weakness: CWE-647 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N