This vulnerability involves a NULL pointer dereference in the libsoup HTTP client library triggered by processing a malformed WWW-Authenticate header in a 401 Unauthorized response. An attacker can exploit this by hosting a malicious HTTP server that sends this crafted response, causing the client application using libsoup to crash, resulting in denial-of-service. The vulnerability affects Red Hat Enterprise Linux 10 and has a medium severity rating with a CVSS 3.1 base score of 4.3. The vendor advisory is published by Red Hat but does not provide explicit patch or fix information.

Successful exploitation causes a denial-of-service condition by crashing the client application using the vulnerable libsoup library. There is no impact on confidentiality or integrity. The attack requires user interaction in the form of connecting to a malicious server. No known active exploitation has been reported.

Patch status is not yet confirmed—check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2025-4476 for the latest remediation guidance. Until an official fix is available, users should avoid connecting to untrusted or suspicious HTTP servers that could send malicious 401 responses with crafted WWW-Authenticate headers.