CVE-2024-43491 is a critical use-after-free vulnerability (CWE-416) identified in the servicing stack component of Microsoft Windows 10 Version 1507, specifically affecting Windows 10 Enterprise 2015 LTSB and Windows 10 IoT Enterprise 2015 LTSB editions. The vulnerability emerged because recent servicing stack updates rolled back previous fixes for vulnerabilities in optional components, effectively reintroducing exploitable conditions. This rollback affects systems that installed the March 12, 2024 security update (KB5035858) or other updates released until August 2024. The use-after-free flaw allows an unauthenticated remote attacker to execute arbitrary code with system-level privileges without requiring user interaction, potentially leading to full compromise of the affected system’s confidentiality, integrity, and availability. The vulnerability does not impact later Windows 10 versions, which have maintained the fixes. Microsoft addressed the issue by releasing a September 2024 servicing stack update (KB5043936) and a corresponding security update (KB5043083), which must be installed in order to fully remediate the vulnerability. Notably, Windows 10 Version 1507 reached end of support for most editions in May 2017, leaving only the Enterprise 2015 LTSB and IoT Enterprise 2015 LTSB editions under support and vulnerable. No known active exploits have been reported, but the critical CVSS score of 9.8 reflects the high severity and ease of exploitation. Organizations running these legacy Windows 10 versions should urgently apply the patches to mitigate the risk.

The impact of CVE-2024-43491 is severe, as exploitation allows remote attackers to execute arbitrary code at system level without any authentication or user interaction. This can lead to complete system compromise, including unauthorized access to sensitive data, disruption of system operations, and potential deployment of malware or ransomware. Since the vulnerability affects servicing stack components, it could also undermine the integrity of future updates and system stability. Organizations relying on Windows 10 Enterprise 2015 LTSB and Windows 10 IoT Enterprise 2015 LTSB editions are at significant risk, especially if they have installed the vulnerable updates from March to August 2024. The vulnerability poses a critical threat to industries with legacy systems that have not migrated to newer Windows versions, including manufacturing, healthcare, and critical infrastructure sectors. The lack of required privileges or user interaction lowers the barrier for exploitation, increasing the likelihood of attacks if patches are not applied promptly.

To mitigate CVE-2024-43491, organizations must install the September 2024 servicing stack update (KB5043936) first, followed by the September 2024 Windows security update (KB5043083) in that exact order. This sequence is critical to fully restore the previous fixes and eliminate the use-after-free vulnerability. Organizations should inventory their Windows 10 systems to identify any running Version 1507 Enterprise or IoT Enterprise LTSB editions and prioritize patch deployment on these devices. Given the end of support for most editions of Version 1507, organizations should also plan to migrate to supported Windows versions to reduce future risk. Additionally, monitoring network traffic and endpoint behavior for unusual activity can help detect potential exploitation attempts. Employing network segmentation and limiting exposure of vulnerable systems to untrusted networks can further reduce attack surface. Regular backups and incident response readiness are recommended to mitigate potential damage from exploitation.