CVE-2025-54099 is a stack-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). The vulnerability arises due to improper handling of input data in the driver, which leads to a buffer overflow on the stack. This overflow can be exploited by an authorized local attacker with low privileges to execute arbitrary code or escalate privileges to SYSTEM level. The vulnerability does not require user interaction but has a high attack complexity, meaning exploitation requires detailed knowledge of the system and conditions. The flaw affects confidentiality, integrity, and availability by potentially allowing attackers to gain full control over the affected system. Although no public exploits are known, the vulnerability is classified as high severity with a CVSS v3.1 score of 7.0, reflecting its significant impact if exploited. The affected version is an early release of Windows 10 (Version 1507), which is largely considered legacy and may no longer be supported with security updates. No official patches or mitigations have been published yet, increasing the risk for systems that remain unpatched. This vulnerability is tracked under CWE-121, which covers stack-based buffer overflows, a common and dangerous class of memory corruption bugs.

If exploited, this vulnerability allows a local attacker with limited privileges to escalate their privileges to SYSTEM level, effectively gaining full control over the affected Windows 10 system. This can lead to unauthorized access to sensitive data, installation of persistent malware, disruption of system operations, and potential lateral movement within a network. The compromise of confidentiality, integrity, and availability can severely impact organizations relying on legacy Windows 10 systems, especially those with critical infrastructure or sensitive information. Since the vulnerability requires local access, the threat is more significant in environments where multiple users share systems or where attackers can gain initial footholds through other means. The lack of patches increases the window of exposure, and organizations that have not upgraded from Windows 10 Version 1507 remain vulnerable. This can affect operational continuity, compliance posture, and increase the risk of data breaches or ransomware attacks.

1. Restrict local access to systems running Windows 10 Version 1507 to trusted users only, minimizing the risk of local exploitation. 2. Employ application whitelisting and endpoint protection solutions that can detect and block suspicious privilege escalation attempts. 3. Monitor system logs and security events for unusual activity indicative of exploitation attempts targeting WinSock or privilege escalation. 4. Disable or limit use of legacy Windows 10 Version 1507 systems where possible, migrating to supported and patched Windows versions. 5. Implement strict user account control policies to reduce the number of users with local privileges. 6. Use network segmentation to isolate vulnerable systems from critical infrastructure and sensitive data. 7. Stay informed on Microsoft’s security advisories for this CVE and apply patches or official mitigations immediately upon release. 8. Consider deploying host-based intrusion prevention systems (HIPS) that can detect buffer overflow exploitation techniques. 9. Conduct regular vulnerability assessments and penetration tests focusing on privilege escalation vectors. 10. Educate users and administrators about the risks of running unsupported operating system versions and the importance of timely updates.