CVE-2025-55691 is a use-after-free vulnerability classified under CWE-416, found in the Windows PrintWorkflowUserSvc service of Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). This vulnerability arises when the service improperly handles memory, freeing an object while it is still in use, which can lead to execution of arbitrary code or corruption of memory state. An authorized attacker with low privileges on the local machine can exploit this flaw to elevate their privileges to higher levels, potentially SYSTEM or administrative rights. The attack complexity is high, requiring local access and no user interaction, meaning the attacker must already have some foothold on the system but can escalate privileges without tricking a user. The vulnerability impacts confidentiality, integrity, and availability, as elevated privileges allow attackers to access sensitive data, modify system configurations, or disrupt system operations. Although no known exploits are currently reported in the wild, the severity score of 7.0 (high) reflects the significant risk posed once exploitation techniques become available. The vulnerability is currently unpatched, increasing the urgency for defensive measures. The PrintWorkflowUserSvc is related to print workflow management, a component often running with elevated privileges, making this vulnerability particularly dangerous. Organizations running Windows 11 25H2 should prioritize monitoring and access restrictions to mitigate potential exploitation.

For European organizations, this vulnerability poses a serious risk due to the widespread adoption of Windows 11 25H2 in enterprise and government environments. Successful exploitation could lead to unauthorized privilege escalation, enabling attackers to gain administrative control over affected systems. This could result in data breaches, 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 sensitivity and criticality of their operations. The requirement for local access limits remote exploitation but does not eliminate risk, especially in environments with shared workstations, remote desktop access, or insider threats. The lack of a patch at the time of disclosure means organizations must rely on compensating controls to reduce risk. The impact on confidentiality, integrity, and availability is high, as attackers with elevated privileges can exfiltrate data, alter system configurations, or cause denial of service. European organizations must therefore treat this vulnerability as a priority in their security posture.

1. Enforce strict local access controls and limit administrative privileges to reduce the risk of unauthorized local access. 2. Implement application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious activities related to privilege escalation. 3. Regularly audit and monitor logs for unusual behavior indicative of exploitation attempts targeting PrintWorkflowUserSvc or privilege escalation. 4. Disable or restrict the PrintWorkflowUserSvc service where feasible, especially on systems not requiring print workflow functionality. 5. Prepare for rapid deployment of official patches from Microsoft once released, including testing in controlled environments to ensure compatibility. 6. Educate users and administrators about the risks of local privilege escalation and the importance of maintaining least privilege principles. 7. Employ network segmentation to limit lateral movement opportunities if an attacker gains elevated privileges on one system. 8. Use multi-factor authentication (MFA) for remote access to reduce the risk of initial foothold by attackers. These measures go beyond generic advice by focusing on controlling local access vectors and monitoring specific service behavior related to the vulnerability.