CVE-2025-54793 PoC — Astro: Duplicate trailing slash feature can lead to Open Redirects

Title:Astro: Duplicate trailing slash feature can lead to Open Redirects (CVE-2025-54793)
Description:Astro is a web framework for content-driven websites. In versions 5.2.0 through 5.12.7, there is an Open Redirect vulnerability in the trailing slash redirection logic when handling paths with double slashes. This allows an attacker to redirect users to arbitrary external domains by crafting URLs such as https://mydomain.com//malicious-site.com/. This increases the risk of phishing and other social engineering attacks. This affects sites that use on-demand rendering (SSR) with the Node or Cloudflare adapters. It does not affect static sites, or sites deployed to Netlify or Vercel. This issue is fixed in version 5.12.8. To work around this issue at the network level, block outgoing redirect responses with a Location header value that starts with `//`.

Astro 5.2.0 through 5.12.7 contains an open redirect caused by improper handling of paths with double slashes in trailing slash redirection logic, letting attackers redirect users to arbitrary external domains, exploit requires on-demand SSR with Node or Cloudflare adapters.

 id: CVE-2025-54793

info:
  name: Astro SSR - Open Redirect
  author: DhiyaneshDk
  severity: medium

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