CVE-2025-21295: 
vulnerability analysis and mitigation

SPNEGO Extended Negotiation (NEGOEX) Security Mechanism Remote Code Execution Vulnerability (CVE-2025-21295) is a critical vulnerability affecting Windows systems. The vulnerability was disclosed in January 2025 and has a CVSS score of 8.1. This vulnerability affects SPNEGO (Simple and Protected GSSAPI Negotiation Mechanism) Extended Negotiation Security Mechanism, which is used for secure negotiation of authentication protocols between clients and servers (CrowdStrike Blog).

The vulnerability has been assigned a Critical severity rating with a CVSS v3.1 Base Score of 8.1 (HIGH) with the following vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. The vulnerability is associated with CWE-416 (Use After Free) as reported by Microsoft Corporation (NVD).

If successfully exploited, an attacker could execute remote code on the target system without any user interaction, potentially gaining unauthorized control over the affected device. The vulnerability primarily impacts web-based authentication scenarios, particularly with Internet Explorer and IIS (Internet Information Services) (CrowdStrike Blog).

Microsoft has released security updates to address this vulnerability. The affected systems include various versions of Windows 10, Windows 11, and Windows Server installations. Organizations should apply the available patches to affected systems to mitigate the risk (NVD).