CVE-2025-53718 is a high-severity use-after-free vulnerability identified in the Windows Ancillary Function Driver for WinSock component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability arises due to improper handling of memory, where a pointer to a freed memory object is dereferenced, leading to potential memory corruption. This flaw can be exploited by an authorized local attacker to elevate privileges on the affected system. Specifically, the attacker must have limited privileges (local privileges) and does not require user interaction to trigger the vulnerability. The vulnerability is categorized under CWE-416 (Use After Free), which is a common memory corruption issue that can lead to arbitrary code execution or system compromise. The CVSS v3.1 base score is 7.0, reflecting high severity, with vector metrics indicating local attack vector (AV:L), high attack complexity (AC:H), low privileges required (PR:L), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No known exploits are currently reported in the wild, and no patches or updates have been linked yet. The vulnerability was reserved in early July 2025 and published in August 2025, indicating recent discovery and disclosure. The affected product is specifically Windows 10 Version 1809, which is an older Windows 10 release, but still in use in some environments.

For European organizations, this vulnerability poses a significant risk, especially in environments where Windows 10 Version 1809 is still deployed. The ability for a local attacker to escalate privileges can lead to full system compromise, enabling lateral movement, installation of persistent malware, or exfiltration of sensitive data. Critical infrastructure, government agencies, and enterprises relying on legacy Windows 10 systems could be particularly vulnerable. The high impact on confidentiality, integrity, and availability means that successful exploitation could disrupt business operations, lead to data breaches, or compromise critical services. Since the attack requires local access, insider threats or attackers who have gained initial foothold through other means (e.g., phishing, physical access) could leverage this vulnerability to gain elevated privileges. The lack of known exploits in the wild currently reduces immediate risk, but the public disclosure may prompt attackers to develop exploits, increasing the threat over time.

European organizations should prioritize identifying and inventorying systems running Windows 10 Version 1809. Given the absence of an official patch at the time of disclosure, organizations should implement compensating controls such as restricting local user privileges to the minimum necessary, employing application whitelisting, and enhancing monitoring for suspicious local privilege escalation attempts. Network segmentation and strict access controls can limit the ability of attackers to gain local access. Organizations should also prepare to deploy patches promptly once Microsoft releases an update addressing this vulnerability. Additionally, employing endpoint detection and response (EDR) solutions capable of detecting anomalous behavior related to use-after-free exploitation can provide early warning. Regularly updating and hardening systems, disabling unnecessary services related to WinSock ancillary functions if feasible, and conducting user awareness training to prevent initial compromise vectors will further reduce risk.