CVE-2025-29835 is a security vulnerability identified in Microsoft Windows 10 Version 1809, specifically in the Routing and Remote Access Service (RRAS). The vulnerability is classified as an out-of-bounds read (CWE-125), which occurs when a program reads data past the boundary of a buffer. This flaw allows an unauthorized attacker to remotely disclose sensitive information over a network without requiring any privileges. The vulnerability has a CVSS 3.1 base score of 6.5, indicating a medium severity level. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), but requires user interaction (UI:R). The scope remains unchanged (S:U), and the impact is primarily on confidentiality (C:H), with no impact on integrity or availability. The vulnerability affects Windows 10 Version 1809 build 10.0.17763.0. Although no known exploits are currently in the wild, the vulnerability could be leveraged by attackers to extract sensitive information from affected systems remotely, potentially leading to further exploitation or reconnaissance. The absence of a patch link suggests that a fix may not yet be publicly available, increasing the urgency for mitigation measures. The vulnerability is related to improper memory handling in RRAS, a service used to provide routing and remote access capabilities, which is often enabled in enterprise environments for VPN and network management purposes.

For European organizations, this vulnerability poses a significant risk, especially for those relying on Windows 10 Version 1809 in their infrastructure, particularly in network edge devices or VPN gateways using RRAS. The ability for an unauthenticated attacker to remotely disclose sensitive information can lead to exposure of confidential data, network topology, or credentials, facilitating further attacks such as lateral movement or privilege escalation. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, could face compliance risks if sensitive data is leaked. Additionally, the requirement for user interaction, while limiting some attack vectors, does not eliminate risk in environments where social engineering or phishing could trigger the exploit. The medium severity rating suggests that while the vulnerability is not immediately critical, it should be addressed promptly to prevent exploitation, especially given the lack of known patches and exploits. The impact on confidentiality without affecting integrity or availability means that while systems may continue to operate normally, the breach of sensitive information could have long-term reputational and operational consequences.

European organizations should take immediate steps to mitigate this vulnerability beyond generic patching advice. First, verify if Windows 10 Version 1809 systems are still in use, particularly those running RRAS, and prioritize their identification through asset management tools. If possible, upgrade affected systems to a later Windows version or apply any available security updates from Microsoft as soon as they are released. In the interim, consider disabling RRAS on systems where it is not essential to reduce the attack surface. For systems requiring RRAS, implement strict network segmentation and firewall rules to limit RRAS exposure to trusted networks only. Employ network intrusion detection systems (NIDS) with signatures tuned to detect anomalous RRAS traffic patterns that could indicate exploitation attempts. Enhance user awareness training to reduce the risk of social engineering that could trigger user interaction-based exploits. Additionally, monitor network traffic for unusual data exfiltration patterns that may result from out-of-bounds read exploitation. Finally, maintain up-to-date backups and incident response plans tailored to information disclosure incidents to minimize operational impact if exploitation occurs.