CVE-2025-4476 PoC — Libsoup: null pointer dereference in libsoup may lead to denial of service

Title:Libsoup: null pointer dereference in libsoup may lead to denial of service (CVE-2025-4476)
Description:A denial-of-service vulnerability has been identified in the libsoup HTTP client library. This flaw can be triggered when a libsoup client receives a 401 (Unauthorized) HTTP response containing a specifically crafted domain parameter within the WWW-Authenticate header. Processing this malformed header can lead to a crash of the client application using libsoup. An attacker could exploit this by setting up a malicious HTTP server. If a user's application using the vulnerable libsoup library connects to this malicious server, it could result in a denial-of-service. Successful exploitation requires tricking a user's client application into connecting to the attacker's malicious server.

# CVE-2025-4476-Exploit

A small Python test client to send HTTP GET requests with an oversized Authorization: Basic header.
This tool is intended for lab testing and research into header-parsing issues (e.g., null-dereference / crash bugs such as CVE-2025-4476 in libsoup). It demonstrates how a client-server exchange with malformed headers can trigger parsing errors; it is not an exploit framework.

Usage: run against a local or authorized test target only.
Important: use responsibly — do not scan or attack systems without explicit permission.

 [4.0K]  /data/pocs/b015a0342013a559ca051cdb6d4156ed6499b0b0
├── [ 553]  README.md
└── [5.3K]  send_auth_request.py

1 directory, 2 files