CVE-2025-64765: Astro Path Traversal Vulnerability Could Bypass Authentication

Overview

CVE-2025-64765 is a security vulnerability identified in Astro, a modern web framework. This vulnerability involves a path traversal issue arising from a mismatch in how Astro normalizes request paths for routing/rendering versus how middleware reads the path for validation checks. Specifically, it’s been discovered that Astro applies decodeURI() internally for route matching, while middleware uses context.url.pathname without the same decoding. This discrepancy allows attackers to potentially bypass authentication or authorization checks by using specially crafted, encoded paths.

Technical Details

The root cause of the vulnerability lies in the inconsistent path normalization within the Astro framework. When a request is received, Astro internally uses decodeURI() to determine the appropriate route to render. However, when middleware components are configured to perform validation checks (e.g., authentication, authorization), they directly access the path via context.url.pathname, which does not undergo the same URI decoding process. This allows an attacker to craft a request with encoded characters in the path that will be correctly routed by Astro’s routing mechanism but bypassed by middleware that isn’t expecting the encoded characters.

For example, a protected route might be /admin/dashboard. An attacker could use an encoded path like /admin/%252e%252e/dashboard (which decodes to /admin/../dashboard, normalizing to a different route) to potentially bypass middleware checks intended to protect the /admin/dashboard route.

CVSS Analysis

As of the published date of this article, a CVSS score has not been assigned to CVE-2025-64765. However, due to the potential for authentication bypass, the severity is likely to be rated as High or Critical depending on the specific context and affected resources. Further CVSS scoring is pending.

Possible Impact

The exploitation of CVE-2025-64765 could have significant security implications. Successful exploitation may allow attackers to:

• Bypass authentication and access protected resources.
• Gain unauthorized access to sensitive data.
• Perform unauthorized actions within the application.

The impact depends heavily on the specific implementation of middleware and the sensitivity of the protected routes within the Astro application.

Mitigation or Patch Steps

The vulnerability has been addressed in Astro version 5.15.8. It is highly recommended that all Astro users upgrade to version 5.15.8 or later to mitigate the risk of exploitation.

If immediate upgrading is not possible, consider implementing the following workaround:

• Ensure that all middleware components that perform path validation or access control also apply decodeURI() to the context.url.pathname before performing any checks.

However, this workaround is not a substitute for upgrading and should only be considered a temporary measure.

References

GitHub Commit: 6f800813516b07bbe12c666a92937525fddb58ce
GitHub Security Advisory: GHSA-ggxq-hp9w-j794