CVE-2025-29956 is a medium-severity vulnerability identified as a buffer over-read (CWE-126) in the Microsoft Windows 10 Version 1809 SMB (Server Message Block) protocol implementation. This vulnerability allows an authorized attacker with low privileges to remotely disclose sensitive information over a network by exploiting improper bounds checking in SMB packet processing. Specifically, the flaw causes the system to read beyond the intended buffer limits, potentially leaking memory contents that could include sensitive data. The vulnerability requires the attacker to have some level of authentication and user interaction, which limits the ease of exploitation. The CVSS 3.1 base score is 5.4, reflecting a network attack vector with high attack complexity, low privileges required, and user interaction needed. The impact is primarily on confidentiality, as the attacker can gain unauthorized access to information, but it does not affect integrity or availability. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation may rely on workarounds or system hardening until an official update is released. The vulnerability affects Windows 10 Version 1809 build 10.0.17763.0, which is an older Windows 10 release, but still in use in some enterprise environments. Given the SMB protocol's critical role in file sharing and network communications, this vulnerability could be leveraged in targeted attacks to gather sensitive information from affected systems.

For European organizations, this vulnerability poses a risk of sensitive information disclosure within internal networks or between trusted partners using SMB on Windows 10 Version 1809 systems. Organizations that have not upgraded from this older Windows 10 version or have legacy systems in operation are particularly vulnerable. The information leakage could facilitate further attacks such as credential theft, lateral movement, or espionage, especially in sectors handling sensitive or regulated data like finance, healthcare, and government. The requirement for authentication and user interaction reduces the risk of widespread automated exploitation but does not eliminate targeted attacks by insiders or sophisticated adversaries. Additionally, SMB is commonly used in enterprise environments for file sharing and domain services, so exploitation could impact business continuity and data confidentiality. European organizations with complex IT environments and legacy system dependencies should be especially vigilant, as the vulnerability could be exploited to gain footholds in networks or exfiltrate sensitive information.

1. Prioritize upgrading or patching Windows 10 Version 1809 systems to a more recent, supported Windows version where this vulnerability is resolved. 2. Until patches are available, restrict SMB access to trusted hosts only by implementing strict network segmentation and firewall rules that limit SMB traffic to essential systems. 3. Enforce strong authentication mechanisms and monitor SMB authentication logs for unusual access patterns or failed attempts. 4. Disable SMBv1 if still enabled, as it is deprecated and often increases attack surface. 5. Employ endpoint detection and response (EDR) solutions to detect anomalous SMB traffic or memory access patterns indicative of exploitation attempts. 6. Educate users about the risks of interacting with unsolicited SMB shares or network prompts to reduce the likelihood of user interaction-based exploitation. 7. Regularly audit and inventory systems running Windows 10 Version 1809 to identify and remediate legacy systems. 8. Implement network intrusion detection systems (NIDS) with signatures tuned to detect SMB anomalies related to buffer over-read attempts.