How severe is CVE-2025-66202?

CVE-2025-66202 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2025-66202 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66202?

CVE-2025-66202 affects Astro. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66202?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-66202 have an EU (EUVD) identifier?

Yes. CVE-2025-66202 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201717.

When was CVE-2025-66202 published?

CVE-2025-66202 was published on 2025-12-09 and last updated on 2026-06-17.

CVE-2025-66202

CVE-2025-66202 is a medium-severity vulnerability in Astro with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-647.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201717
Weakness: CWE-647
Affected product: Astro
Published: 2025-12-09
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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.
How severe is CVE-2025-66202?: CVE-2025-66202 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2025-66202 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66202?: CVE-2025-66202 affects Astro. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66202?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66202 have an EU (EUVD) identifier?: Yes. CVE-2025-66202 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201717.
When was CVE-2025-66202 published?: CVE-2025-66202 was published on 2025-12-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:astro:astro:*:*:*:*:*:node.js:*:*

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