CVE-2025-56383 is a DLL hijacking vulnerability identified in Notepad++ version 8.8.3. DLL hijacking occurs when an attacker places a malicious Dynamic Link Library (DLL) file in a location where the application loads DLLs, causing the application to load the malicious DLL instead of the legitimate one. In this case, Notepad++ improperly handles the loading of DLL files, allowing an attacker to replace or insert a malicious DLL that the application will execute. This vulnerability enables an attacker to execute arbitrary code with the privileges of the user running Notepad++. Since Notepad++ is a widely used text editor on Windows systems, this vulnerability can be exploited by placing a malicious DLL in a directory that Notepad++ searches for DLLs, such as the working directory or system paths. The attacker could leverage this by tricking a user into opening a specially crafted folder or file, or by placing the DLL in a location accessible to the user. The vulnerability does not require user authentication but may require user interaction to trigger the execution, such as opening Notepad++ or a specific file. There is no CVSS score assigned yet, and no known exploits in the wild have been reported as of the publication date. No patch or mitigation guidance has been officially released at the time of this report.

For European organizations, this vulnerability poses a significant risk primarily to endpoint security. Since Notepad++ is commonly used by developers, IT staff, and general users, exploitation could lead to arbitrary code execution on affected machines, potentially allowing attackers to install malware, steal sensitive information, or move laterally within networks. The impact on confidentiality is high if attackers gain access to sensitive documents or credentials stored or accessed via compromised endpoints. Integrity could be compromised if attackers modify files or configurations. Availability impact is medium, as attackers could disrupt user productivity or deploy ransomware. The lack of authentication requirement increases risk, but the need for user interaction somewhat limits automated exploitation. However, in environments where users frequently open untrusted files or directories, the risk is elevated. European organizations with large Windows-based workforces using Notepad++ are particularly vulnerable, especially in sectors with high security requirements such as finance, government, and critical infrastructure.

Organizations should immediately audit their environments to identify systems running Notepad++ version 8.8.3. Until an official patch is released, practical mitigations include: 1) Restricting write permissions on directories where Notepad++ loads DLLs to prevent unauthorized DLL placement. 2) Educating users to avoid opening untrusted folders or files that could contain malicious DLLs. 3) Employing application whitelisting and endpoint protection solutions that can detect or block unauthorized DLL loads. 4) Running Notepad++ with least privilege to limit the impact of code execution. 5) Monitoring systems for suspicious DLL files or unusual process behavior related to Notepad++. 6) Considering temporary replacement of Notepad++ with alternative editors if usage is not critical. Once a patch is available, prompt deployment is essential. Additionally, organizations should review their incident response plans to address potential exploitation scenarios involving DLL hijacking.