CVE-2025-32013: LNbits Lightning Network Payment System Vulnerable to Server-Side Request Forgery via LNURL Authentication Callback

A Server-Side Request Forgery (SSRF) vulnerability has been discovered in LNbits’ LNURL authentication handling functionality. The vulnerability exists in the LNURL authentication callback process where the application makes HTTP requests to user-provided callback URLs and follows redirects without proper validation.

When processing LNURL authentication requests, the application accepts a callback URL parameter and makes an HTTP request to that URL using the httpx library with redirect following enabled. The application doesn’t properly validate the callback URL, allowing attackers to specify internal network addresses and access internal resources.

This vulnerability allows an attacker to make the application send HTTP requests to arbitrary internal network locations, potentially exposing sensitive information or accessing internal services that should not be accessible from the internet.