CVE-2025-59837: 
JavaScript vulnerability analysis and mitigation

CVE-2025-59837 affects Astro, a web framework, in versions 5.13.4 and later before 5.13.10. The vulnerability is related to the image proxy domain validation which can be bypassed using backslashes in the href parameter. This vulnerability is a patch bypass of a previous vulnerability (CVE-2025-58179) (GitHub Advisory).

The vulnerability exists in Astro's image proxy functionality where the domain validation can be bypassed by using backslashes () in the href parameter. This bypass allows server-side requests to arbitrary URLs, despite previous patches that blocked http://, https://, and // schemes. The vulnerability has been assigned a CVSS v3.1 base score of 7.2 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N (NVD).

The vulnerability can lead to Server-Side Request Forgery (SSRF) attacks, allowing attackers to make server-side requests to arbitrary URLs. Additionally, there is potential for Cross-Site Scripting (XSS) attacks. This dual impact makes the vulnerability particularly concerning for web applications using the affected versions of Astro (GitHub Advisory).

The vulnerability has been fixed in Astro version 5.13.10. Users are strongly advised to upgrade to this version to mitigate the security risk. The fix was implemented through commits 1e2499e and 9ecf359.