CVE-2025-13566 is a vulnerability classified as a double free in the nnn file manager, an efficient terminal-based file browser widely used in Unix-like environments. The issue resides in the functions show_content_in_floating_window and run_cmd_as_plugin within the source file nnn/src/nnn.c. A double free occurs when the program attempts to free the same memory location twice, leading to memory corruption, which can cause application crashes or potentially be leveraged for arbitrary code execution under certain conditions. However, exploitation requires local access with at least low-level privileges (PR:L) and does not require user interaction or authentication. The CVSS 4.0 vector indicates low attack complexity and no privileges required beyond local access, with no impact on confidentiality, integrity, or availability beyond local application stability. The vulnerability affects versions 5.0 and 5.1 of nnn, and a patch has been committed (commit ID 2f07ccdf21e705377862e5f9dfa31e1694979ac7) to address the issue. No known exploits are currently reported in the wild, suggesting limited active exploitation. The vulnerability's impact is primarily on application stability and potential denial of service on affected systems.

For European organizations, the impact of CVE-2025-13566 is primarily related to local system stability rather than direct compromise of sensitive data or widespread service disruption. Since nnn is a terminal-based file manager often used by developers, system administrators, and power users on Linux and Unix systems, the vulnerability could lead to crashes or unexpected behavior when using the affected functions. This may disrupt workflows or cause temporary denial of service on local machines. The requirement for local access and low privileges limits the risk of remote exploitation or large-scale attacks. However, in environments where nnn is used on critical systems or by privileged users, exploitation could be leveraged as part of a multi-stage attack chain. The absence of known exploits reduces immediate risk but patching is important to prevent future abuse. Organizations relying on open-source tooling and Linux-based infrastructure should prioritize remediation to maintain operational stability.

1. Immediately apply the official patch identified by commit 2f07ccdf21e705377862e5f9dfa31e1694979ac7 to all affected nnn installations (versions 5.0 and 5.1). 2. If patching is not immediately possible, restrict local access to systems running nnn to trusted users only, minimizing the risk of exploitation. 3. Implement strict user privilege management to ensure that only necessary users have access to nnn and related tools. 4. Monitor local system logs and application behavior for crashes or anomalies that could indicate exploitation attempts. 5. Educate users about the risks of running untrusted commands or plugins within nnn, as the vulnerability involves run_cmd_as_plugin. 6. Consider deploying application whitelisting or sandboxing techniques to limit the impact of potential memory corruption. 7. Maintain up-to-date backups and recovery procedures to mitigate any disruption caused by crashes or denial of service. 8. Regularly review and update local security policies to reduce the attack surface for local vulnerabilities.