CVE-2025-21257 is a medium-severity vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0), specifically affecting the WLAN AutoConfig service. The vulnerability is classified as an out-of-bounds read (CWE-125), which occurs when the software reads data beyond the boundaries of allocated memory buffers. This flaw can lead to information disclosure, as the WLAN AutoConfig service may inadvertently expose sensitive information from memory. The CVSS v3.1 base score is 5.5, reflecting a medium severity level. The attack vector is local (AV:L), requiring low attack complexity (AC:L) and low privileges (PR:L), but no user interaction (UI:N). The scope remains unchanged (S:U), and the impact is high on confidentiality (C:H), with no impact on integrity or availability (I:N, A:N). No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was published on January 14, 2025, with the reservation date on December 10, 2024. The WLAN AutoConfig service manages wireless network connections, and this vulnerability could allow a local attacker with limited privileges to read sensitive memory contents, potentially exposing credentials or other confidential data related to wireless configurations.

For European organizations, this vulnerability poses a risk primarily to systems still running the outdated Windows 10 Version 1809, which is past its mainstream support lifecycle. The information disclosure could lead to leakage of sensitive wireless network configuration data, including credentials or security tokens, which could facilitate further lateral movement or network reconnaissance by attackers. Organizations in sectors with high reliance on wireless connectivity, such as finance, healthcare, and critical infrastructure, may face increased risk if attackers leverage this vulnerability to gain footholds or escalate privileges. Although exploitation requires local access and low privileges, insider threats or attackers who have already compromised a low-privilege account could exploit this flaw to escalate their information gathering capabilities. The absence of known exploits and patches suggests that the threat is currently theoretical but should be addressed proactively to prevent future exploitation.

Given the lack of an official patch at this time, European organizations should implement several practical mitigations: 1) Upgrade affected systems from Windows 10 Version 1809 to a supported and patched Windows version to eliminate exposure. 2) Restrict local access to systems by enforcing strict access controls and monitoring for unauthorized logins, especially on devices handling sensitive wireless configurations. 3) Employ endpoint detection and response (EDR) solutions to detect anomalous local activities that could indicate attempts to exploit memory vulnerabilities. 4) Harden wireless network security by using strong authentication methods (e.g., WPA3) and network segmentation to limit the impact of any information disclosure. 5) Educate users and administrators about the risks of running unsupported OS versions and the importance of timely updates. 6) Monitor security advisories from Microsoft for the release of patches or workarounds and apply them promptly once available.