CVE-2025-54911 is a high-severity use-after-free vulnerability (CWE-416) identified in Microsoft Windows 10 Version 1809, specifically in the BitLocker component. BitLocker is a full disk encryption feature designed to protect data by providing encryption for entire volumes. The vulnerability arises when the system improperly handles memory management, leading to a use-after-free condition. This means that after a memory object is freed, the system continues to use the pointer referencing that memory, which can lead to unpredictable behavior including memory corruption. An authorized attacker with local access and limited privileges can exploit this flaw to elevate their privileges on the affected system. The CVSS v3.1 base score is 7.3, indicating a high severity level. The attack vector is local (AV:L), requiring low attack complexity (AC:L) and privileges (PR:L), but user interaction is required (UI:R). The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning successful exploitation could lead to full system compromise. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability affects Windows 10 Version 1809 build 17763.0, which is an older version of Windows 10, but still in use in some environments. The flaw could be leveraged by attackers to bypass security controls enforced by BitLocker, potentially exposing encrypted data or allowing unauthorized system modifications.

For European organizations, this vulnerability poses a significant risk, especially for those still running Windows 10 Version 1809 in their infrastructure. The ability to elevate privileges locally means that any user or malware with limited access could gain higher-level control, potentially leading to data breaches, ransomware deployment, or disruption of critical services. Since BitLocker is widely used in enterprise environments across Europe to secure sensitive data, exploitation could undermine data confidentiality and integrity, violating GDPR and other data protection regulations. The high impact on availability could also disrupt business operations. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitive nature of their data and the regulatory environment. Additionally, the requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk from insider threats or malware that gains initial foothold with limited privileges.

European organizations should prioritize upgrading or patching affected systems as soon as Microsoft releases an official fix. In the absence of a patch, organizations should implement strict access controls to limit local user privileges and restrict the installation and execution of untrusted software. Employing application whitelisting and endpoint detection and response (EDR) solutions can help detect and prevent exploitation attempts. Regularly auditing systems to identify devices running Windows 10 Version 1809 and planning for their upgrade to supported Windows versions is critical. Additionally, enforcing multi-factor authentication and network segmentation can reduce the risk of lateral movement following privilege escalation. Monitoring for unusual local privilege escalation activities and educating users about the risks of interacting with untrusted content can further mitigate exploitation chances. Finally, organizations should ensure that BitLocker recovery keys are securely stored and managed to prevent data loss in case of compromise.