CVE-2025-55303 Unauthorized third-party images in Astro’s _image endpoint
Attackers can bypass third-party domain restrictions in Astro's image endpoint using protocol-relative URLs, serving unauthorized images.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-55303?
CVE-2025-55303 is a medium-severity vulnerability in withastro astro, published on 19 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Astro is a web framework for content-driven websites. In versions of astro before 5.13.2 and 4.16.18, the image optimization endpoint in projects deployed with on-demand rendering allows images from unauthorized third-party domains to be served. On-demand rendered sites built with Astro include an /_image endpoint which returns optimized versions of images. A bug in impacted versions of astro allows an attacker to bypass the third-party domain restrictions by using a protocol-relative URL as the image source, e.g. /_image?href=//example.com/image.png. This vulnerability is fixed in 5.13.2 and 4.16.18.
Which versions are affected by CVE-2025-55303?
6 open source packages ship an affected version, including astro and @astrojs/node. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
astro npm | All versions | 4.16.19 |
astro npm | All versions | 4.16.19 |
astro npm | From 5.0.0-alpha.0 | 5.13.2 |
astro npm | From 5.0.0-alpha.0 | 5.13.2 |
@astrojs/node npm | All versions | 9.1.1 |
@astrojs/node npm | All versions | 9.1.1 |
Products include Astro Astro.
How do I fix CVE-2025-55303?
Upgrade astro to a fixed version for your release line: 4.16.19 or 5.13.2.
Is CVE-2025-55303 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-55303 exists.
Public exploit code: 1 Nuclei template.
Other vulnerabilities in withastro astro
- CVE-2024-56159 Server source code is exposed to the public if sourcemaps are enabled
- CVE-2026-54299 Astro: Host header SSRF in prerendered error page fetch
- CVE-2025-59837 astro allows bypass of image proxy domain validation leading to SSRF and potential XSS
- CVE-2026-50146 Astro: Reflected XSS via unescaped slot name
- CVE-2025-64764 Astro is vulnerable to Reflected XSS via the server islands feature
Sources
Also known as GHSA-xf8x-j4p2-f749.