CVE-2025-59242 is a heap-based buffer overflow vulnerability identified in the Windows Ancillary Function Driver for WinSock component of Microsoft Windows 10 Version 1507 (build 10.0.10240.0). This vulnerability arises from improper handling of memory buffers in the WinSock driver, which is responsible for network socket operations. An authorized local attacker can exploit this flaw by triggering a buffer overflow condition, leading to memory corruption. This corruption can be leveraged to execute arbitrary code with elevated privileges, effectively allowing privilege escalation from a lower-privileged user context to SYSTEM level. The vulnerability does not require user interaction but does require local access and existing privileges, making it a local privilege escalation (LPE) vector. The CVSS v3.1 base score is 7.8, reflecting high severity due to the potential for full system compromise. Although no public exploits are currently known, the vulnerability's presence in an older Windows 10 version means that legacy systems remain at risk. The lack of available patches at the time of publication suggests that mitigation relies on system upgrades or workarounds until official fixes are released. This vulnerability is categorized under CWE-122 (Heap-based Buffer Overflow), indicating a classic memory corruption issue that can lead to arbitrary code execution and system compromise.

The primary impact of CVE-2025-59242 is local privilege escalation, which can allow attackers with limited access to gain SYSTEM-level privileges. This can lead to full control over affected systems, enabling attackers to install persistent malware, disable security controls, exfiltrate sensitive data, or pivot within networks. The vulnerability affects Windows 10 Version 1507, a legacy release that may still be operational in some industrial, governmental, or enterprise environments where upgrades are delayed. Exploitation could compromise confidentiality, integrity, and availability of affected systems. Organizations relying on this version for critical infrastructure or legacy applications face increased risk of targeted attacks. Although no known exploits are reported, the high severity and ease of exploitation by authorized users make this a significant threat. The scope is limited to local users, so remote exploitation is not feasible without prior access. However, once local access is obtained, the attacker can escalate privileges and potentially compromise entire networks.

To mitigate CVE-2025-59242, organizations should prioritize upgrading affected systems from Windows 10 Version 1507 to a supported and patched Windows version, as no patches are currently available for this legacy build. If upgrading is not immediately feasible, consider applying any available security workarounds such as restricting local user permissions, disabling unnecessary services related to WinSock ancillary drivers, and enforcing strict application whitelisting to prevent execution of unauthorized code. Employ endpoint detection and response (EDR) solutions to monitor for suspicious local privilege escalation attempts. Regularly audit local user accounts and privileges to minimize the number of users with local access. Network segmentation can limit the impact of compromised systems. Additionally, maintain up-to-date backups to enable recovery in case of compromise. Organizations should monitor Microsoft advisories for forthcoming patches and apply them promptly once released. Finally, conduct targeted security awareness training to reduce the risk of initial local access by attackers.