CVE-2025-11947 is a heap-based buffer overflow vulnerability identified in the bftpd FTP server, specifically affecting versions 6.0, 6.1, and 6.2. The vulnerability resides in the expand_groups function within the options.c file, part of the configuration file handler component. This function improperly manages memory when processing group expansions, allowing an attacker to manipulate inputs to trigger a heap overflow. The overflow could potentially lead to arbitrary code execution or cause the service to crash, impacting availability. However, exploitation requires local access to the host and is considered highly complex due to the need for precise manipulation of the heap memory layout. No user interaction or authentication is needed beyond limited local privileges. The vendor has not responded to the disclosure, and no patches are currently available. Although a public exploit exists, no widespread exploitation in the wild has been reported. The CVSS 4.0 score is 2.0, reflecting the high attack complexity and limited scope of impact. The vulnerability does not affect confidentiality, integrity, or availability significantly under typical conditions, but it remains a risk for environments where local user access is possible and bftpd is deployed.

For European organizations, the primary impact is on systems running bftpd versions 6.0 to 6.2 where local user access is granted. The vulnerability could allow a local attacker to execute arbitrary code or cause denial of service via a crash, potentially disrupting FTP services. This could impact internal file transfer operations, especially in organizations relying on bftpd for legacy or specialized FTP services. Confidentiality and integrity impacts are limited given the local access requirement and complexity. However, disruption of FTP services could affect business continuity and internal workflows. Organizations with multi-user environments or shared hosting where local access is possible are at higher risk. The lack of vendor response and patches increases exposure duration. While the threat is not critical, it requires attention in environments where bftpd is in use, particularly in sectors with sensitive data transfers or regulatory compliance obligations.

1. Restrict local user access to systems running bftpd to trusted personnel only, minimizing the attack surface. 2. Monitor system logs and FTP server logs for unusual behavior or crash events that may indicate exploitation attempts. 3. Employ host-based intrusion detection systems (HIDS) to detect anomalous heap manipulation or memory corruption attempts. 4. Consider isolating bftpd services in containers or virtual machines to limit potential damage from exploitation. 5. If possible, replace bftpd with alternative FTP servers that are actively maintained and patched. 6. Regularly audit and update system configurations to minimize unnecessary local user privileges. 7. Stay alert for vendor updates or community patches and apply them promptly once available. 8. Implement strict access controls and network segmentation to limit local access to critical FTP servers. 9. Conduct internal security training to raise awareness about the risks of local privilege exploitation. 10. Prepare incident response plans for potential exploitation scenarios involving local privilege escalation or denial of service.