CVE-2025-61925: 
JavaScript vulnerability analysis and mitigation

CVE-2025-61925 affects Astro web framework versions prior to 5.14.2. The vulnerability was discovered and disclosed on October 10, 2025, and involves the improper validation of the X-Forwarded-Host header value when using Astro.url. This security issue affects applications using Astro in on-demand/dynamic rendering mode behind a caching proxy (GitHub Advisory).

The vulnerability stems from Astro reflecting the value in X-Forwarded-Host in output when using Astro.url without proper validation. When web servers like nginx route requests via the Host header and forward other request headers, a malicious request can be sent containing both a Host header and an X-Forwarded-Host header with mismatched values, where the X-Forwarded-Host header contains malicious content. The vulnerability has been assigned a CVSS v3.1 score of 6.5 (Medium) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L (GitHub Advisory).

The vulnerability can lead to manipulation of any code using the Astro.url value. For example, canonical links can be manipulated to point to malicious sites, and login/registration form URLs could potentially redirect credentials to unauthorized parties. While initially affecting only the malicious user's request, when used with a caching proxy, the manipulated values can be persisted and served to subsequent users, expanding the attack surface (GitHub Advisory).

The vulnerability has been patched in Astro version 5.14.2. Users should upgrade to this version or later to mitigate the risk. Other frameworks typically implement an allowlist of domains for validation or avoid header reflection entirely to prevent such issues (GitHub Advisory).