Executive brief
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.
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
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