CVE-2025-25568 is a critical use-after-free vulnerability identified in SoftEtherVPN version 5.02.5187, specifically within the Command.c file's CheckNetworkAcceptThread function. Use-after-free (CWE-416) vulnerabilities occur when a program continues to use a pointer after the memory it points to has been freed, potentially leading to arbitrary code execution, crashes, or data corruption. This vulnerability has a CVSS 3.1 base score of 9.8, indicating a critical severity level with network attack vector, low attack complexity, no privileges required, no user interaction, and impacts on confidentiality, integrity, and availability. However, the supplier disputes the vulnerability's applicability to the VPN software itself, clarifying that the use-after-free exists in a separate stress-testing tool for the networking stack. This tool reportedly does not process untrusted input and operates under the user's own privileges, which may limit the practical exploitability of the vulnerability in typical VPN deployments. No patches have been published yet, and no known exploits are in the wild. The vulnerability was reserved in early February 2025 and published in March 2025. The lack of affected version details beyond the stated 5.02.5187 version and the supplier's dispute suggest that the risk may be confined to specific use cases involving the stress-testing tool rather than the core VPN service. Nevertheless, given the critical CVSS score and the nature of use-after-free vulnerabilities, organizations using SoftEtherVPN or its associated tools should carefully assess their exposure and monitor for updates or patches.

For European organizations, the impact of CVE-2025-25568 depends heavily on whether the vulnerable stress-testing tool is deployed in their environments. If the tool is not used or is isolated from untrusted inputs, the risk is minimal. However, if organizations employ this tool for network stack testing, the vulnerability could allow remote attackers to execute arbitrary code, leading to full compromise of affected systems. This could result in data breaches, disruption of VPN services, and potential lateral movement within networks. Given SoftEtherVPN's use in various sectors including government, finance, and healthcare across Europe, exploitation could undermine secure remote access infrastructure, impacting confidentiality and availability of critical communications. The critical severity and network-level exploitability without authentication mean that vulnerable systems exposed to the internet could be targeted by attackers to gain unauthorized access or disrupt services. The supplier's note that the vulnerable component runs with user privileges and does not accept untrusted input somewhat mitigates the risk, but organizations should not dismiss the threat, especially in environments where the stress-testing tool is used or where custom configurations might expose the vulnerability.

1. Inventory and Audit: Identify all instances of SoftEtherVPN and any associated stress-testing tools deployed within the organization. Confirm whether the vulnerable stress-testing tool is in use. 2. Restrict Access: Limit network exposure of the stress-testing tool to trusted internal networks only, preventing external or untrusted access. 3. Privilege Management: Ensure that the stress-testing tool runs with the least privileges necessary, ideally under non-administrative user accounts, to reduce impact if exploited. 4. Monitor for Updates: Maintain close monitoring of SoftEtherVPN vendor advisories and CVE databases for patches or official guidance addressing this vulnerability. 5. Disable or Remove: If the stress-testing tool is not essential, disable or uninstall it to eliminate the attack surface. 6. Network Segmentation: Isolate systems running the stress-testing tool from critical infrastructure to contain potential exploitation. 7. Logging and Detection: Enhance logging around the use of the stress-testing tool and monitor for anomalous behavior that could indicate exploitation attempts. 8. Incident Response Preparedness: Prepare response plans for potential exploitation scenarios, including forensic readiness and containment strategies.