CVE-2025-55303: Astro

Medium severity, CVSS 6.1. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Astro Astro: before 4.16.18 (fixed in 4.16.18); from 5.0.0, before 5.13.2 (fixed in 5.13.2)

Published 2025-08-19. Last modified 2026-06-17.