CVE-2025-55701 is a vulnerability classified under CWE-1287, indicating improper validation of specified input types within Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). This flaw allows an authorized local attacker—meaning someone with existing access to the system but with limited privileges—to escalate their privileges to a higher level, potentially SYSTEM or administrator. The vulnerability stems from Windows failing to correctly validate the type of input it processes, which can be manipulated by an attacker to bypass security controls. The CVSS v3.1 base score is 7.8, with vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating local attack vector, low attack complexity, required privileges are low, no user interaction needed, unchanged scope, and high impact on confidentiality, integrity, and availability. No public exploits or patches are currently available, increasing the risk window. The vulnerability could be leveraged to gain unauthorized access to sensitive data, modify system configurations, or disrupt system availability. Since it requires local access, initial compromise vectors could include phishing, physical access, or exploitation of other vulnerabilities. The lack of user interaction requirement makes automated or stealthy privilege escalation feasible once local access is obtained.

For European organizations, this vulnerability poses a significant risk due to the widespread adoption of Windows 11 25H2 in enterprise environments. Successful exploitation could allow attackers to gain administrative privileges, leading to full system compromise. This can result in data breaches, unauthorized data manipulation, disruption of critical services, and potential lateral movement within networks. Sectors such as finance, healthcare, government, and critical infrastructure are particularly vulnerable due to the sensitive nature of their data and services. The absence of known exploits currently provides a window for proactive mitigation, but the high severity score and ease of exploitation mean that once exploited, the impact could be severe. Organizations relying on Windows 11 25H2 without additional endpoint protections or monitoring are at increased risk of undetected privilege escalation attacks.

1. Implement strict input validation and sanitization at all levels where possible, especially for local processes handling user or system inputs. 2. Employ the principle of least privilege to limit user permissions and reduce the attack surface for privilege escalation. 3. Monitor and audit local privilege escalation attempts using endpoint detection and response (EDR) tools and Windows event logs focusing on suspicious process behavior and privilege changes. 4. Apply defense-in-depth strategies such as application whitelisting, controlled folder access, and exploit protection features available in Windows Defender Exploit Guard. 5. Segment networks to limit lateral movement opportunities if an escalation occurs. 6. Stay informed about official Microsoft patches or mitigations and apply them promptly once released. 7. Educate users and administrators about the risks of local privilege escalation and enforce strong physical and logical access controls to prevent unauthorized local access. 8. Consider deploying virtual desktop infrastructure (VDI) or sandboxing for high-risk user activities to contain potential exploits.