CVE-2025-64765: Astro middleware authentication bypass via URL encoding

CVE-2025-64765 · Severity: medium · CVSS 5.3 · Published 2025-11-19

Astro is a JavaScript framework used to build fast web applications. A flaw in how Astro processes URL paths allows attackers to bypass authentication checks in middleware by using URL-encoded characters (e.g., %61 for 'a'). An attacker can reach protected routes like /admin by crafting requests with encoded paths that the routing system decodes but the authentication checks do not, leading to unauthorized access to administrative or sensitive functionality.

Technologies: Astro, astro (npm). Vendors: Astro, npm.

Quick answers

Is CVE-2025-64765 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2025-64765 being exploited in the wild.
How severe is CVE-2025-64765?
Medium severity, with a CVSS score of 5.3, published 19 November 2025.
Which products and versions are affected?
astro (npm) SEMVER:introduced=0,fixed=5.15.8.
Is there a fix for CVE-2025-64765?
Yes. astro (npm): upgrade to 5.15.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-64765 attacked?
It is attacked over the network.
Am I affected by CVE-2025-64765?
Check whether you run Astro or astro (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • astro (npm): upgrade to 5.15.8 or later
    npm install astro@5.15.8

Technical details

The vulnerability is a path normalization bypass (CWE-22) in Astro's middleware handling. Astro internally decodes URL paths using decodeURI() before routing requests to the correct page, but the middleware context.url.pathname is not similarly decoded. This creates a mismatch: an attacker sending GET /%61dmin (where %61 is the URL encoding of 'a') will be routed to /admin internally but fail middleware authentication checks that compare against the undecoded path string. The attacker gains access to protected routes without meeting authentication requirements. The fix applies decodeURI() consistently to the path before passing it to middleware context. Affected versions are all releases before 5.15.8, which includes the patch.

Affected products

  • Astro Astro < 5.15.8

Identifiers

  • CVE-2025-64765
  • GHSA-ggxq-hp9w-j794

Timeline

  • 2025-11-19: disclosed
  • 2025-11-19: patched: Fixed in version 5.15.8
  • 2025-02-04: other: Advisory modified on GitHub

References

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