CVE-2025-59295 is a heap-based buffer overflow vulnerability classified under CWE-122, affecting Internet Explorer running on Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). The vulnerability arises from improper handling of memory buffers in Internet Explorer, which can be exploited by an attacker to execute arbitrary code remotely without requiring authentication. The attack vector is network-based, typically involving the victim visiting a maliciously crafted webpage or receiving malicious content that triggers the overflow. Successful exploitation can lead to full compromise of the affected system, impacting confidentiality, integrity, and availability. The vulnerability has a CVSS v3.1 base score of 8.8, reflecting its high severity, with attack complexity low, no privileges required, but user interaction necessary. Although Internet Explorer is largely deprecated, it remains present in Windows 11 for legacy compatibility, making this vulnerability relevant for environments still relying on it. No public exploits have been reported yet, but the potential for weaponization is significant given the nature of the flaw. The absence of an official patch at the time of publication necessitates immediate risk mitigation strategies. This vulnerability highlights the ongoing risks posed by legacy components embedded in modern operating systems and the importance of minimizing their exposure.

For European organizations, this vulnerability poses a critical risk especially to sectors relying on Windows 11 with legacy Internet Explorer components, such as government, finance, healthcare, and critical infrastructure. Exploitation could lead to unauthorized remote code execution, enabling attackers to deploy malware, ransomware, or conduct espionage. The compromise of sensitive data and disruption of services could have severe operational and reputational consequences. Given the network-based attack vector and lack of required privileges, the vulnerability could be exploited at scale if weaponized. Organizations with remote workforce or those that allow Internet Explorer for legacy applications are particularly vulnerable. The impact extends to supply chains and partners using affected systems, increasing the risk of lateral movement within networks. The high CVSS score underscores the urgency of addressing this vulnerability to prevent potential widespread exploitation in Europe.

Until an official patch is released, European organizations should take immediate steps to mitigate risk: 1) Disable Internet Explorer completely or restrict its use via Group Policy and application control to prevent access to untrusted content. 2) Employ network-level protections such as web filtering and intrusion prevention systems to block malicious URLs and payloads targeting Internet Explorer. 3) Enforce strict endpoint security controls including application whitelisting and behavior-based detection to identify exploitation attempts. 4) Educate users about the risks of interacting with unknown links or attachments, emphasizing the need to avoid Internet Explorer for browsing. 5) Monitor network and endpoint logs for suspicious activity indicative of exploitation attempts. 6) Where legacy applications require Internet Explorer, consider isolating these systems in segmented network zones with limited internet access. 7) Prepare for rapid deployment of patches once Microsoft releases updates by maintaining an up-to-date asset inventory and patch management process. These targeted mitigations go beyond generic advice by focusing on legacy component isolation and proactive detection.