CVE-2024-26242 is a high-severity elevation of privilege vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability is categorized under CWE-591, which involves sensitive data storage in improperly locked memory. Specifically, this flaw exists within the Windows Telephony Server component, which handles telephony-related services and APIs. The vulnerability arises because sensitive data is stored in memory regions that are not properly locked, allowing lower-privileged processes or users to potentially access or manipulate this data. Exploiting this vulnerability requires local access (attack vector: local), with a high attack complexity and low privileges needed, but no user interaction is required. The impact is significant, as successful exploitation can lead to full compromise of confidentiality, integrity, and availability of the affected system, allowing an attacker to elevate privileges and execute arbitrary code with higher privileges. Although no known exploits are currently observed in the wild, the vulnerability’s characteristics and the critical nature of the affected component make it a serious threat. The lack of available patches at the time of publication increases the urgency for mitigation. The vulnerability’s CVSS v3.1 score is 7.0, reflecting its high severity with partial network restrictions and the need for local access, but with high impact on system security.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and public sector entities still running Windows 10 Version 1809, which is an older but still in-use version in some environments. Successful exploitation could allow attackers to gain elevated privileges on affected systems, potentially leading to unauthorized access to sensitive data, disruption of telephony services, and broader system compromise. This could impact confidentiality of communications, integrity of telephony-related operations, and availability of critical services. Sectors relying on telephony infrastructure for internal communications, customer support, or emergency services could face operational disruptions. Additionally, organizations with strict data protection requirements under GDPR may face compliance risks if sensitive data is exposed. The vulnerability’s requirement for local access limits remote exploitation but does not eliminate risk from insider threats or attackers who have gained initial footholds through other means. The absence of known exploits in the wild currently reduces immediate risk but does not preclude future exploitation, especially as threat actors develop proof-of-concept exploits.

1. Upgrade or patch: Organizations should prioritize upgrading affected systems to a supported and patched version of Windows 10 or later, as no patches are currently linked to this CVE. Monitor Microsoft security advisories closely for the release of official patches. 2. Restrict local access: Limit local user accounts and enforce strict access controls to reduce the risk of local exploitation. Use endpoint protection solutions to detect and prevent unauthorized privilege escalation attempts. 3. Application whitelisting: Implement application control policies to prevent execution of unauthorized code that could leverage this vulnerability. 4. Telephony service hardening: Disable or restrict Windows Telephony Server services on systems where telephony functionality is not required. 5. Monitor logs: Enable detailed logging and monitor for unusual activity related to privilege escalation or telephony services. 6. Network segmentation: Isolate critical systems running Windows 10 Version 1809 to limit lateral movement opportunities for attackers with local access. 7. User education: Train users to recognize and report suspicious activity that could indicate attempts to exploit local vulnerabilities. 8. Incident response readiness: Prepare to respond quickly to any detected exploitation attempts, including forensic analysis and containment.