CVE-2025-59837: Astro image proxy domain validation bypass leading to SSRF and XSS

CVE-2025-59837 · Severity: high · CVSS 7.2 · Published 2025-10-28

Astro's image optimization proxy failed to fully block unsafe URL schemes in a security patch, allowing attackers to bypass validation using backslashes and access arbitrary internal resources or inject malicious content. This vulnerability could enable an attacker to access internal services or deliver malware-laden images to end users through a web application using Astro.

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

Quick answers

Is CVE-2025-59837 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2025-59837 being exploited in the wild.
How severe is CVE-2025-59837?
High severity, with a CVSS score of 7.2, published 28 October 2025.
Which products and versions are affected?
astro (npm) SEMVER:introduced=5.13.4,fixed=5.13.10.
Is there a fix for CVE-2025-59837?
Yes. astro (npm): upgrade to 5.13.10 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-59837 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2025-59837?
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 5.13.10 or later
    npm install astro@5.13.10

Technical details

The vulnerability is a patch bypass of CVE-2025-58179 in Astro's image proxy endpoint. The initial fix blocked http://, https://, and // prefixes, but an attacker can bypass this using backslashes (\) as a URL prefix alternative, allowing the server-side request to reach arbitrary domains. This results in Server-Side Request Forgery (SSRF) and Cross-Site Scripting (XSS) impacts. The vulnerable versions are 5.13.4 through 5.13.9 of Astro; the issue requires network access to the affected application's image proxy endpoint with no authentication required. An attacker can craft a malicious image request to extract sensitive data from internal services or inject malicious SVG/image content that executes in users' browsers.

Affected products

  • Astro Astro 5.13.4 to 5.13.9

Identifiers

  • CVE-2025-59837
  • GHSA-qcpr-679q-rhm2

Timeline

  • 2025-10-28: disclosed: Advisory published
  • 2025-10-28: patched: Fix released in Astro 5.13.10
  • 2025-10-28: other: CVE-2025-59837 assigned

References

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