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CVE-2025-66202

Astro has an Authentication Bypass via Double URL Encoding, a bypass for CVE-2025-64765

Published: Dec 8, 2025Updated: Dec 10, 2025 Sources: CVE List NVD GHSACWE-647
NVD MITRE
6.5CVSSMEDIUM
EPSS Score
0.3%
Top 81.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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 Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-647

Affected Products

astrowithastro
Library
OSS Libraries / web-framework
astronpmOSS Libraries
astroastro
Mixed
OSS Libraries / web-framework
withastrooss-projectOSS Librariesaka astro, @astrojs/cloudflare
npmpackage-ecosystemOSS Libraries
astrooss-projectUSOSS Librariesaka @astrojs/node, @astrojs/cloudflare

Exploitability

Official Patch Available

References

https://github.com/withastro/astro/security/advisories/GHSA-whqg-ppgf-wp8c
github.com
https://github.com/withastro/astro/security/advisories/GHSA-ggxq-hp9w-j794
github.com
https://github.com/withastro/astro/commit/6f800813516b07bbe12c666a92937525fddb58ce
github.com
and 3 more references View all →

Timeline

Published
Dec 8, 2025
Last Updated
Dec 10, 2025

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