CVE-2025-49661 is a vulnerability classified under CWE-822 (Untrusted Pointer Dereference) affecting Microsoft Windows 10 Version 1507 (build 10.0.10240.0). The flaw resides in the Windows Ancillary Function Driver for WinSock, a component responsible for network socket operations. An untrusted pointer dereference occurs when the driver dereferences a pointer that can be controlled or influenced by an attacker, leading to undefined behavior such as memory corruption. This vulnerability can be exploited by an authorized local attacker to elevate privileges on the affected system. The attacker does not require user interaction, and the attack complexity is low, meaning exploitation is feasible with moderate skill. The vulnerability impacts confidentiality, integrity, and availability, potentially allowing the attacker to execute arbitrary code with elevated privileges, modify system files, or cause system instability. The CVSS v3.1 base score is 7.8, reflecting high severity with local attack vector, low attack complexity, and privileges required but no user interaction. No public exploits or patches are currently available, indicating a window of exposure. The vulnerability is specific to an older Windows 10 release (Version 1507), which is out of mainstream support, increasing risk for organizations still running this version. The flaw underscores the importance of secure pointer handling in kernel-mode drivers and the risks posed by legacy software components.

The primary impact of CVE-2025-49661 is local privilege escalation on affected Windows 10 Version 1507 systems. Successful exploitation allows an attacker with authorized local access to gain SYSTEM-level privileges, effectively compromising the entire system. This can lead to unauthorized access to sensitive data, installation of persistent malware, disabling of security controls, and disruption of system availability. Organizations relying on legacy Windows 10 installations, especially in environments where multiple users have local access or where endpoint security is weak, face increased risk. The vulnerability could be leveraged as a stepping stone for lateral movement within networks or to bypass security restrictions. Although no known exploits are currently in the wild, the availability of a public CVE and detailed technical information may prompt attackers to develop exploits. The lack of patches exacerbates the risk, particularly for critical infrastructure, government, and enterprise environments that have not upgraded to newer Windows versions. Overall, the threat undermines system integrity and confidentiality and poses a significant operational risk.

1. Upgrade affected systems from Windows 10 Version 1507 to a supported and fully patched Windows version to eliminate exposure to this vulnerability. 2. Until upgrades are possible, restrict local user access to trusted personnel only and enforce strict access controls to minimize the risk of local exploitation. 3. Implement application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious local privilege escalation attempts. 4. Regularly audit and monitor system logs for unusual activities indicative of privilege escalation or memory corruption exploits. 5. Disable or limit the use of legacy network components or drivers if feasible, especially the Windows Ancillary Function Driver for WinSock, through system configuration or group policies. 6. Apply any security updates or patches released by Microsoft promptly once available. 7. Conduct user training to reduce the risk of unauthorized local access and reinforce security best practices. 8. Employ virtualization or sandboxing for legacy applications requiring the affected OS version to isolate potential exploitation impacts.