CVE-2024-21311 is a medium-severity vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). It is classified as an out-of-bounds read vulnerability (CWE-125) within the Windows Cryptographic Services component. This flaw allows an attacker with limited privileges (local access with low complexity) to read memory outside the intended buffer boundaries. The vulnerability does not require user interaction and does not affect system integrity or availability but can lead to high-impact information disclosure. Specifically, the attacker could leverage this flaw to access sensitive cryptographic information or other protected data residing in memory, potentially compromising confidentiality. The CVSS v3.1 score is 5.5, reflecting a medium severity with a vector indicating local attack vector, low attack complexity, and requiring privileges but no user interaction. There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability was reserved in December 2023 and published in January 2024. Given the affected product is an older Windows 10 version (1809), which is still in use in some environments, this vulnerability poses a risk primarily to organizations that have not upgraded to newer Windows versions or applied relevant security updates.

For European organizations, the impact of CVE-2024-21311 centers on potential unauthorized disclosure of sensitive cryptographic material or other confidential data stored in memory by Windows Cryptographic Services. This could undermine the confidentiality of encrypted communications, authentication tokens, or cryptographic keys, potentially facilitating further attacks such as privilege escalation or lateral movement. Organizations in sectors with high security requirements—such as finance, healthcare, government, and critical infrastructure—may face increased risks if legacy Windows 10 1809 systems remain in operation. The vulnerability's local attack vector means that attackers would need some level of access to the target system, which could be achieved through compromised user accounts or insider threats. Although the vulnerability does not directly affect system integrity or availability, the information disclosure could lead to secondary attacks with more severe consequences. The absence of known exploits reduces immediate risk, but the medium severity and potential for sensitive data leakage warrant prompt attention.

European organizations should prioritize upgrading affected systems from Windows 10 Version 1809 to a supported and fully patched Windows version to eliminate exposure. In environments where immediate upgrade is not feasible, organizations should implement strict access controls to limit local user privileges and reduce the risk of unauthorized local access. Employing endpoint detection and response (EDR) solutions can help identify suspicious local activities indicative of exploitation attempts. Network segmentation and application whitelisting can further reduce the attack surface. Monitoring for unusual memory access patterns or cryptographic service anomalies may provide early warning signs. Organizations should stay alert for official patches or security advisories from Microsoft and apply them promptly once available. Additionally, conducting regular audits to identify legacy systems and ensuring compliance with security policies will help mitigate risks associated with this vulnerability.