CVE-2025-55335 is a use-after-free vulnerability classified under CWE-416, found in the NTFS file system driver of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises when the system improperly manages memory, freeing an object while it is still in use, which can be exploited by a local attacker to execute arbitrary code with elevated privileges. The attacker does not require any prior authentication or user interaction, but the attack complexity is high, indicating that exploitation requires detailed knowledge of the system internals and precise timing. Successful exploitation could allow an attacker to gain SYSTEM-level privileges, compromising confidentiality, integrity, and availability of the affected system. The vulnerability is currently not known to be exploited in the wild, but given the severity and potential impact, it represents a significant risk. The lack of available patches at the time of disclosure means organizations must implement interim mitigations and prepare for prompt patch deployment. The vulnerability affects a legacy Windows 10 version that is still in use in some environments, especially where upgrade cycles are slow or constrained by compatibility requirements.

For European organizations, this vulnerability poses a serious risk, especially in sectors where legacy Windows 10 Version 1809 systems remain operational, such as manufacturing, healthcare, and government agencies. Exploitation could lead to unauthorized privilege escalation, enabling attackers to bypass security controls, access sensitive data, disrupt operations, or deploy ransomware and other malware. The high impact on confidentiality, integrity, and availability could result in data breaches, operational downtime, and regulatory non-compliance under GDPR. Organizations with limited patch management capabilities or those that allow broad local access to systems are particularly vulnerable. The absence of known exploits currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits over time. The vulnerability also increases the attack surface for insider threats or malware that gains initial local access through other means.

Organizations should immediately inventory their Windows 10 systems to identify those running Version 1809 (build 10.0.17763.0). Until patches are released, restrict local access to these systems by enforcing strict access controls and using endpoint protection solutions to detect suspicious activity. Employ application whitelisting and limit administrative privileges to reduce the risk of privilege escalation. Monitor system logs for unusual behavior indicative of exploitation attempts. Prepare for rapid deployment of security updates once Microsoft releases patches. Consider upgrading affected systems to a supported and fully patched Windows version to eliminate exposure. Additionally, implement network segmentation to isolate legacy systems and reduce potential lateral movement by attackers exploiting this vulnerability.