CVE-2025-54093 is a high-severity vulnerability identified as a Time-of-Check to Time-of-Use (TOCTOU) race condition affecting the TCP/IP stack in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises when the system performs a security check on a resource or condition (time-of-check) but the state of that resource changes before the system uses it (time-of-use), allowing an attacker to exploit the timing gap. Specifically, this flaw exists within the Windows TCP/IP implementation, where an authorized local attacker with limited privileges can manipulate the timing to elevate their privileges. The vulnerability is classified under CWE-367, which covers TOCTOU race conditions that can lead to inconsistent or unexpected behavior due to changes in resource state between check and use operations. The CVSS v3.1 base score is 7.0, indicating a high severity, with the vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C. This means the attack requires local access (AV:L), high attack complexity (AC:H), low privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), and impacts confidentiality, integrity, and availability to a high degree (C:H/I:H/A:H). The exploitability is considered official (RL:O) and the report is confirmed (RC:C). No known exploits are currently in the wild, and no patches have been linked yet. The vulnerability allows an attacker to escalate privileges locally by exploiting the race condition in the TCP/IP stack, potentially gaining SYSTEM-level access or similar, which could lead to full system compromise. This is particularly concerning because the TCP/IP stack is a core component of Windows networking, and exploitation could affect network-related processes and services. Since Windows 10 Version 1809 is an older release, many organizations may have already moved to newer versions, but legacy systems remain at risk. The absence of user interaction requirement and the ability to elevate privileges locally make this vulnerability a significant threat in environments where unprivileged users have local access.

For European organizations, the impact of CVE-2025-54093 can be substantial, especially in sectors relying on legacy Windows 10 Version 1809 systems. Privilege escalation vulnerabilities allow attackers to gain higher-level access, potentially leading to unauthorized data access, system manipulation, and disruption of critical services. Confidentiality, integrity, and availability of sensitive data and systems could be compromised. This is particularly critical for industries such as finance, healthcare, government, and critical infrastructure, where Windows 10 1809 may still be in use due to legacy application dependencies or slow upgrade cycles. Attackers exploiting this vulnerability could bypass security controls, deploy malware, move laterally within networks, and exfiltrate sensitive information. The lack of known exploits in the wild currently provides a window for proactive mitigation, but the high severity and ease of local exploitation mean that insider threats or attackers with initial local access could leverage this vulnerability effectively. Additionally, the vulnerability could be used as a stepping stone in multi-stage attacks targeting European organizations, increasing the overall risk posture.

1. Upgrade and Patch: Organizations should prioritize upgrading Windows 10 Version 1809 systems to a supported and updated Windows version where this vulnerability is fixed. If patches become available, apply them promptly. 2. Restrict Local Access: Limit local user accounts and enforce strict access controls to minimize the number of users who can execute code locally on vulnerable systems. 3. Use Application Control: Implement application whitelisting and endpoint protection solutions to prevent unauthorized code execution that could exploit the race condition. 4. Monitor for Suspicious Activity: Deploy advanced monitoring and logging to detect unusual privilege escalation attempts or anomalous TCP/IP stack behavior. 5. Network Segmentation: Isolate legacy systems to reduce the risk of lateral movement if an attacker exploits this vulnerability. 6. Harden TCP/IP Stack Usage: Where possible, disable or restrict unnecessary network services and protocols on vulnerable systems to reduce the attack surface. 7. Conduct Security Awareness: Educate users about the risks of local privilege escalation and enforce policies to prevent execution of untrusted code. 8. Incident Response Preparedness: Develop and test incident response plans specifically addressing local privilege escalation scenarios to ensure rapid containment and remediation.