CVE-2025-64765 is a medium severity path traversal vulnerability identified in the Astro web framework, a popular tool for building web applications. The root cause is a mismatch in how request paths are normalized: Astro internally applies decodeURI() to the request path to determine routing, while the middleware responsible for validation checks uses context.url.pathname without the same decoding. This discrepancy allows attackers to craft encoded path variants that Astro routes correctly but that bypass middleware validation, effectively enabling unauthorized access to protected routes. Since the vulnerability does not require authentication, user interaction, or special privileges, it can be exploited remotely over the network. The vulnerability is classified under CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), which typically allows attackers to access files or routes outside intended boundaries. Although no known exploits are currently reported in the wild, the flaw could be leveraged to access sensitive application endpoints or data. The issue affects all Astro versions prior to 5.15.8, where the vendor has implemented a patch to ensure consistent path normalization between routing and middleware validation. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N) indicates network attack vector, low attack complexity, no privileges or user interaction required, and low impact on confidentiality, with no impact on integrity or availability.

For European organizations, this vulnerability poses a risk of unauthorized access to protected routes within web applications built on vulnerable Astro versions. This can lead to exposure of sensitive data or internal functionality that should be restricted, potentially resulting in data breaches or unauthorized operations. Given Astro's growing popularity in modern web development, especially in startups and enterprises adopting JavaScript frameworks, the impact could be significant where Astro is used in production environments. The vulnerability's ease of exploitation without authentication increases risk, particularly for public-facing applications. While the direct impact on confidentiality is low, the ability to bypass access controls can be leveraged as a stepping stone for further attacks or data exposure. Organizations handling personal data under GDPR must consider the compliance implications of such unauthorized access. The lack of known exploits reduces immediate risk but should not lead to complacency.

European organizations should immediately upgrade all Astro framework instances to version 5.15.8 or later, where the vulnerability is patched. Additionally, review and harden middleware validation logic to ensure consistent path normalization, ideally applying decodeURI() or equivalent decoding before validation checks. Implement strict input validation and canonicalization for all incoming request paths to prevent encoded path bypasses. Conduct thorough security testing, including fuzzing and penetration testing, focusing on path traversal and access control bypass scenarios. Employ web application firewalls (WAFs) with rules targeting path traversal attempts and unusual encoded URL patterns. Monitor application logs for suspicious access patterns involving encoded paths. Educate development teams about the importance of consistent path handling between routing and middleware layers. Finally, maintain an inventory of web applications using Astro to ensure timely patching and vulnerability management.