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Vulnerability record · CVE-2025-66202 · published 9 December 2025

CVE-2025-66202: Astro vulnerability

Astro · Astro

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.

6.5 CVSS 3.1 Medium EPSS 0.31% · top 78.2% CWE-647 · CWE-647
6.5CVSS 3.1 base score
0.31%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
17 Jun 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/withastro/astro/commit/6f800813516b07bbe12c666a92937525fddb58ce Patch
https://github.com/withastro/astro/security/advisories/GHSA-ggxq-hp9w-j794 Not Applicable
https://github.com/withastro/astro/security/advisories/GHSA-whqg-ppgf-wp8c Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-66202), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.