CVE-2025-55303

MEDIUM EXPLOITED NUCLEI

Astro < 4.16.18 and 5.0.0-alpha.0-5.13.2 - Unauthorized Image Serving via Protocol-Relative URL Bypass

Title source: llm

Exploitation Summary

CVE-2025-55303 has been observed exploited in the wild (reported by VulnCheck KEV). A Nuclei detection template is also available.

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.

Nuclei Templates (1)

Astro - Unauthorized Third-Party Image Access

MEDIUMVERIFIEDby theamanrawat

Shodan: http.html:"astro"

References (2)

Core 2

Core References

Exploit, Vendor Advisory x_refsource_confirm

https://github.com/withastro/astro/security/advisories/GHSA-xf8x-j4p2-f749

Patch x_refsource_misc

https://github.com/withastro/astro/commit/4d16de7f95db5d1ec1ce88610d2a95e606e83820

View Patch ZIP pw:eip

Scores

CVSS v3 6.1

EPSS 0.0013

EPSS Percentile 32.8%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CISA SSVC

Vulnrichment

Exploitation poc

Automatable yes

Technical Impact partial

Details

VulnCheck KEV 2026-02-12

CWE

CWE-115 CWE-79

Status published

Products (3)

astro/astro < 4.16.18

astrojs/node 0 - 9.1.1npm

npm/astro 5.0.0-alpha.0 - 5.13.2npm

Published Aug 19, 2025

Tracked Since Feb 18, 2026