CVE-2025-29967 is a high-severity heap-based buffer overflow vulnerability identified in the Microsoft Windows App Client for Windows Desktop, specifically affecting version 1.00. The vulnerability resides in the Remote Desktop Gateway Service component, which is responsible for facilitating secure remote connections to internal network resources. A heap-based buffer overflow occurs when data exceeding the allocated buffer size is written to the heap memory, potentially overwriting adjacent memory and enabling arbitrary code execution. In this case, an unauthorized attacker can exploit this vulnerability remotely over the network without requiring prior authentication, although user interaction is required to trigger the exploit. Successful exploitation allows the attacker to execute arbitrary code with high privileges, compromising the confidentiality, integrity, and availability of the affected system. The CVSS v3.1 base score of 8.8 reflects the critical nature of this vulnerability, with network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The scope is unchanged (S:U), and the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). No known exploits are currently reported in the wild, and no official patches have been linked yet, indicating that mitigation efforts should be prioritized to prevent exploitation once active attacks emerge.

For European organizations, this vulnerability poses a significant risk, especially for enterprises relying on Remote Desktop Gateway Services for remote access and teleworking solutions. Exploitation could lead to full system compromise, data breaches, lateral movement within corporate networks, and disruption of critical services. Given the widespread adoption of Microsoft Windows in Europe, including government agencies, financial institutions, healthcare providers, and industrial sectors, the potential impact is broad and severe. Confidential information could be exfiltrated, operational technology could be disrupted, and ransomware or other malware could be deployed post-exploitation. The requirement for user interaction may limit automated exploitation but does not eliminate risk, as social engineering or phishing campaigns could facilitate triggering the vulnerability. The lack of current known exploits offers a window for proactive defense, but the high severity score demands immediate attention to prevent exploitation in the European threat landscape.

European organizations should implement the following specific mitigation measures: 1) Immediately inventory and identify all systems running the affected Windows App Client version 1.00, particularly those exposing Remote Desktop Gateway Services to external networks. 2) Restrict network exposure of Remote Desktop Gateway Services by implementing strict firewall rules, VPN requirements, and network segmentation to limit access only to trusted users and devices. 3) Employ multi-factor authentication (MFA) for all remote access to reduce the risk of user interaction exploitation. 4) Monitor network traffic and system logs for unusual activity related to Remote Desktop Gateway connections, including anomalous user behavior or unexpected code execution attempts. 5) Prepare for rapid deployment of patches or updates from Microsoft once available; in the meantime, consider temporary disabling or limiting the use of the vulnerable service if feasible. 6) Conduct user awareness training focused on recognizing social engineering attempts that could trigger the vulnerability. 7) Utilize endpoint detection and response (EDR) solutions to detect and block exploitation attempts targeting heap-based buffer overflows. These targeted actions go beyond generic advice by focusing on reducing attack surface, enhancing detection, and preparing for patch management specific to this vulnerability.