CVE-2024-21417 is a high-severity elevation of privilege vulnerability affecting Microsoft Windows 10 Version 1809, specifically within the Windows Text Services Framework (TSF). The vulnerability is classified under CWE-862, which indicates a missing authorization issue. This means that the affected component does not properly enforce authorization checks, allowing an attacker with limited privileges (low-level privileges) to escalate their permissions on the system. The CVSS 3.1 base score is 8.8, reflecting a high impact on confidentiality, integrity, and availability, with a complexity that is low and requiring only limited privileges but no user interaction. The vulnerability has a scope change (S:C), meaning the exploit can affect resources beyond the initially compromised component. The attack vector is local (AV:L), requiring the attacker to have local access with some privileges (PR:L). The vulnerability does not require user interaction (UI:N), and the exploitability is currently unknown (E:U), with remediation level official (RL:O) and report confidence confirmed (RC:C). Although no known exploits are reported in the wild yet, the vulnerability poses a significant risk due to the potential for privilege escalation, which can lead to full system compromise if exploited. The affected version is Windows 10 Version 1809 (build 10.0.17763.0), an older but still in-use operating system version in some environments. The Windows Text Services Framework is a core component responsible for managing text input and language services, so exploitation could allow attackers to bypass security controls and execute code or commands with elevated privileges.

For European organizations, this vulnerability presents a serious risk, especially for those still running legacy Windows 10 Version 1809 systems. Successful exploitation could allow attackers to elevate privileges from a low-privilege user to SYSTEM or administrator level, potentially leading to full control over affected machines. This can result in unauthorized access to sensitive data, disruption of business operations, and the deployment of further malware or ransomware. Given the high confidentiality, integrity, and availability impact, critical infrastructure, government agencies, financial institutions, and enterprises with sensitive data are at particular risk. The local attack vector means that attackers would need some initial foothold, such as through phishing, compromised credentials, or insider threats, to leverage this vulnerability. The lack of user interaction requirement increases the risk of automated or stealthy exploitation once local access is obtained. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate it, as threat actors may develop exploits rapidly after public disclosure. Organizations with compliance obligations under GDPR and other data protection regulations must prioritize mitigation to avoid data breaches and regulatory penalties.

1. Upgrade or patch: Although no official patch links are provided in the data, organizations should monitor Microsoft’s security advisories closely and apply any available patches or updates for Windows 10 Version 1809 immediately. 2. System upgrade: Consider upgrading affected systems to a more recent and supported Windows version, as Windows 10 Version 1809 is nearing or past end-of-support in many environments, reducing exposure to known vulnerabilities. 3. Least privilege enforcement: Restrict user privileges rigorously to minimize the number of users with local access and limit the ability to execute unauthorized code. 4. Application whitelisting: Implement application control policies to prevent unauthorized or suspicious executables from running, which can mitigate exploitation attempts. 5. Endpoint detection and response (EDR): Deploy advanced endpoint monitoring to detect unusual privilege escalation behaviors or attempts to exploit TSF components. 6. Network segmentation: Limit lateral movement by segmenting networks and restricting access to sensitive systems, reducing the impact of a local compromise. 7. User training and awareness: Educate users about phishing and social engineering risks that could lead to initial local access. 8. Regular vulnerability scanning: Continuously scan systems to identify unpatched or legacy OS versions and prioritize remediation efforts accordingly.