CVE-2025-47981 is a critical heap-based buffer overflow vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw exists within the SPNEGO (Simple and Protected GSSAPI Negotiation Mechanism) Extended Negotiation component, which is involved in network authentication protocols. Specifically, the vulnerability arises when the system improperly handles certain network negotiation messages, leading to a heap-based buffer overflow condition. This overflow can be exploited by an unauthenticated attacker remotely over the network to execute arbitrary code on the affected system without requiring any user interaction or privileges. The vulnerability has a CVSS v3.1 base score of 9.8, indicating a critical severity level with high impact on confidentiality, integrity, and availability. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N). The scope is unchanged (S:U), meaning the vulnerability affects resources under the same security authority. Successful exploitation could allow complete system compromise, including installation of malware, data theft, or disruption of services. Although no known exploits are currently reported in the wild, the critical nature and ease of exploitation make this vulnerability a significant threat. No official patches or mitigation links are provided yet, indicating that affected systems remain vulnerable until updates are released. The vulnerability is classified under CWE-122 (Heap-based Buffer Overflow), a common and dangerous memory corruption issue that can lead to arbitrary code execution.

For European organizations, this vulnerability poses a severe risk due to the widespread use of Windows 10 Version 1809 in enterprise environments, including government, finance, healthcare, and critical infrastructure sectors. Exploitation could lead to unauthorized remote code execution, allowing attackers to gain persistent footholds, exfiltrate sensitive data, disrupt operations, or deploy ransomware. The lack of required authentication and user interaction increases the risk of automated mass exploitation campaigns, potentially affecting large numbers of systems quickly. Organizations relying on legacy Windows 10 versions without updated security patches are particularly vulnerable. The impact extends to confidentiality breaches, integrity violations through unauthorized code execution, and availability disruptions from potential system crashes or denial-of-service conditions. Given the criticality, European entities must prioritize identification and remediation to prevent exploitation that could compromise national security, economic stability, and personal data protection under GDPR regulations.

1. Immediate identification of all systems running Windows 10 Version 1809 (build 10.0.17763.0) within the network using asset management and vulnerability scanning tools. 2. Apply official security patches from Microsoft as soon as they become available; monitor Microsoft security advisories closely. 3. In the absence of patches, implement network-level mitigations such as blocking or restricting inbound traffic to ports and services associated with SPNEGO Extended Negotiation, typically related to SMB and authentication protocols. 4. Employ network segmentation to isolate vulnerable systems from critical assets and limit lateral movement. 5. Enable and enforce strict firewall rules and intrusion detection/prevention systems (IDS/IPS) signatures that can detect anomalous SPNEGO negotiation attempts. 6. Conduct regular security awareness training to ensure administrators recognize signs of exploitation and maintain up-to-date incident response plans. 7. Consider upgrading affected systems to supported Windows versions with ongoing security updates to reduce exposure to legacy vulnerabilities. 8. Monitor logs and network traffic for unusual authentication negotiation patterns that may indicate exploitation attempts.