CVE-2025-49734 is a vulnerability categorized under CWE-923, which pertains to improper restriction of communication channels to intended endpoints. Specifically, this flaw exists in Windows PowerShell on Microsoft Windows 10 Version 1809 (build 17763.0). The vulnerability allows an attacker who already has some local authorization with low privileges to exploit the communication channel mechanism within PowerShell to escalate their privileges to a higher level. This occurs because the communication channel does not adequately restrict connections to intended endpoints, potentially allowing an attacker to redirect or intercept communications to gain elevated access. The CVSS 3.1 base score is 7.0, indicating a high severity level. The vector details show that the attack requires local access (AV:L), has high attack complexity (AC:H), requires low privileges (PR:L), and no user interaction (UI:N). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). No known exploits have been reported in the wild yet, and no patches are currently linked, suggesting that mitigation may rely on forthcoming updates or workarounds. The vulnerability was reserved in June 2025 and published in September 2025, indicating recent discovery and disclosure.

For European organizations, this vulnerability poses a significant risk, particularly to those running legacy or unpatched Windows 10 Version 1809 systems. An attacker with local access—such as an insider threat, a compromised user account, or malware that has gained limited foothold—could leverage this flaw to escalate privileges, potentially gaining administrative control. This could lead to unauthorized access to sensitive data, disruption of critical services, or further lateral movement within networks. Sectors with high reliance on Windows 10 1809, including government agencies, financial institutions, healthcare, and critical infrastructure, are particularly vulnerable. The high impact on confidentiality, integrity, and availability means that exploitation could result in data breaches, system outages, or manipulation of critical processes. Given the lack of known exploits currently, the threat is more theoretical but should be addressed proactively to prevent future attacks.

Organizations should prioritize upgrading or patching Windows 10 Version 1809 systems as soon as Microsoft releases an official fix. Until patches are available, restrict local access to affected systems by enforcing strict access controls and monitoring user activities, especially those involving PowerShell usage. Implement application whitelisting and restrict PowerShell execution policies to limit unauthorized script execution. Employ endpoint detection and response (EDR) solutions to detect anomalous PowerShell communication patterns indicative of exploitation attempts. Regularly audit and review user privileges to minimize the number of accounts with local access rights. Network segmentation can also help contain potential lateral movement if exploitation occurs. Finally, maintain up-to-date backups and incident response plans to mitigate impact in case of successful exploitation.