Executive brief
Astro's image processing feature includes an option to automatically fetch remote images to determine their dimensions. A flaw in this feature bypasses the developer's configured domain restrictions, allowing an attacker to trick the server into fetching content from any host—including internal services and cloud metadata endpoints. This could expose sensitive information or facilitate attacks on internal infrastructure.
Technical details
The vulnerability is a Server-Side Request Forgery (CWE-918) in Astro's image pipeline. The inferSize option, which fetches remote images at render time to infer their dimensions, fails to enforce the image.domains and image.remotePatterns allowlist restrictions that should control which hosts can be accessed. An attacker who can influence the image URL parameter (via CMS content, user input, or other untrusted sources) can cause the server to make HTTP requests to arbitrary hosts. The vulnerability affects @astrojs/node versions 9.0.0 through 9.5.3 and is fixed in 9.5.4 and later.
Affected products
- Astro @astrojs/node 9.0.0 to 9.5.3
Timeline
- 2026-02-25: disclosed
- 2026-02-25: patched: Fixed in @astrojs/node 9.5.4