CVE-2025-54793: 
JavaScript vulnerability analysis and mitigation

Astro, a web framework for content-driven websites, contains an Open Redirect vulnerability (CVE-2025-54793) in versions 5.2.0 through 5.12.7. The vulnerability exists in the trailing slash redirection logic when handling paths with double slashes, allowing attackers to redirect users to arbitrary external domains. The issue was discovered and disclosed on August 7, 2025, affecting sites using on-demand rendering (SSR) with Node or Cloudflare adapters (GitHub Advisory).

The vulnerability occurs when the target path starts with //. When a request is made to a URL like https://example.com//page, the system sends a Location: //page/ header in the redirect response. The browser interprets this as a protocol-relative URL, redirecting to https://page/ instead of the intended https://example.com//page/. By crafting URLs in the form https://example.com//target.domain/subpath, attackers can cause redirects to arbitrary domains. The exact URL format needed varies based on the trailingSlash setting. The vulnerability has been assigned a CVSS v4.0 score of 5.5 (Medium) (NVD).

This Open Redirect vulnerability (CWE-601) affects any user who clicks on a specially crafted link pointing to the affected domain. Since the domain appears legitimate, victims may be tricked into trusting the redirected page, potentially leading to credential theft, malware distribution, or other phishing-related attacks. The vulnerability can be exploited by unauthenticated users and does not require any special privileges (GitHub Advisory).

The vulnerability has been fixed in version 5.12.8. Organizations should upgrade their Astro installations to this version or later. As a temporary workaround, organizations can implement network-level mitigation by blocking outgoing redirect responses with a Location header value that starts with //. The issue does not affect static sites or sites deployed to Netlify or Vercel (GitHub Advisory).