CVE-2025-47987 is a heap-based buffer overflow vulnerability identified in the Windows Credential Security Support Provider (CredSSP) protocol implementation on Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises due to improper handling of heap memory, allowing an authorized local attacker to overflow a buffer on the heap. Exploiting this flaw can lead to arbitrary code execution with elevated privileges, enabling the attacker to escalate their privileges on the affected system. The vulnerability does not require user interaction but does require the attacker to have some level of local access (low privileges) to the system. The CVSS v3.1 base score is 7.8, indicating a high severity level, with high impact on confidentiality, integrity, and availability. The attack vector is local, and the attack complexity is low, meaning exploitation is feasible without specialized conditions. The vulnerability affects Windows 10 Version 1809, a legacy version of Windows 10, which is still in use in some enterprise environments. No known exploits are currently reported in the wild, and no official patches have been linked yet, though the vulnerability has been publicly disclosed. The heap-based buffer overflow (CWE-122) is a critical memory corruption issue that can be leveraged to execute arbitrary code, potentially leading to full system compromise. Since the vulnerability is local privilege escalation, it is often used as a stepping stone in multi-stage attacks to gain higher privileges after initial access is obtained.

For European organizations, this vulnerability poses a significant risk, especially for those still running Windows 10 Version 1809 in production environments. Successful exploitation can lead to privilege escalation, allowing attackers to bypass security controls, access sensitive data, and disrupt operations. This is particularly concerning for sectors with high-value targets such as finance, government, healthcare, and critical infrastructure, where elevated privileges can facilitate lateral movement and persistent access. The vulnerability's local attack vector means that initial access is required, which could be achieved through phishing, malware, or insider threats. Once exploited, attackers can compromise system integrity and availability, potentially leading to data breaches, ransomware deployment, or sabotage. The lack of a patch increases the urgency for mitigation. Organizations relying on legacy systems or with slow patch management cycles are at higher risk. Additionally, compliance with GDPR and other data protection regulations could be impacted if this vulnerability leads to data exposure or service disruption.

Given the absence of an official patch, European organizations should implement specific mitigations beyond generic advice: 1) Restrict local access strictly by enforcing least privilege principles and limiting administrative rights to essential personnel only. 2) Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious activities indicative of exploitation attempts. 3) Harden CredSSP usage by disabling or restricting remote desktop and other services that rely on CredSSP where possible, or configure them to use alternative authentication protocols. 4) Conduct thorough audits of systems running Windows 10 Version 1809 and prioritize upgrading or migrating to supported Windows versions with active security updates. 5) Implement network segmentation to limit the spread of an attacker who gains local access. 6) Monitor event logs for unusual privilege escalation attempts and anomalous behavior related to authentication services. 7) Educate users and administrators about the risks of local privilege escalation and enforce strong endpoint security hygiene. 8) Prepare incident response plans specifically addressing local privilege escalation scenarios to enable rapid containment.