CVE-2025-54793: Astros's duplicate trailing slash feature leads to an open redirection security issue

There is an Open Redirection 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 Astro >=5.2.0 sites that use on-demand rendering (SSR) with the Node or Cloudflare adapter. It does not affect static sites, or sites deployed to Netlify or Vercel.