CVE-2023-21547: 
vulnerability analysis and mitigation

CVE-2023-21547 is an Internet Key Exchange (IKE) Protocol Denial of Service vulnerability affecting Microsoft Windows systems. The vulnerability was discovered and reported to Microsoft on October 13, 2022, and was publicly disclosed on January 10, 2023 (ZDI Advisory).

The vulnerability exists within the IKEEXT service, which listens on UDP ports 500 and 4500. The specific flaw involves a null pointer dereference that can be triggered by a crafted Vendor ID payload. The vulnerability has been assigned a CVSS score of 3.7 (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L), indicating a relatively low severity but with network-based attack vector requiring no authentication (ZDI Advisory).

When successfully exploited, this vulnerability allows remote attackers to create a denial-of-service condition on the affected system, potentially disrupting network services (ZDI Advisory).

Microsoft has released security updates to address this vulnerability. The fixes are available through various KB updates including KB5022282, KB5022286, KB5022287, KB5022289, KB5022291, KB5022297, and KB5022303 for different versions of Windows 10, Windows 11, and Windows Server (Rapid7).