CVE-2025-66202

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.

CVSS 3.1

6.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 24% of CVEs (scores of 2026-10-25)

CWE

CWE-647

Published

2025-12-09

Modified

2026-10-07

Record from

the NVD, synced 2026-10-19

Affected

• astro:astro

Packages (OSV)

References

• https://github.com/withastro/astro/commit/6f800813516b07bbe12c666a92937525fddb58ce
• https://github.com/withastro/astro/security/advisories/GHSA-ggxq-hp9w-j794
• https://github.com/withastro/astro/security/advisories/GHSA-whqg-ppgf-wp8c

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