CVE-2008-2375 in vsftpd
Summary
by MITRE
Memory leak in a certain Red Hat deployment of vsftpd before 2.0.5 on Red Hat Enterprise Linux (RHEL) 3 and 4, when PAM is used, allows remote attackers to cause a denial of service (memory consumption) via a large number of invalid authentication attempts within the same session, a different vulnerability than CVE-2007-5962.
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Analysis
by VulDB Data Team • 05/29/2025
The vulnerability identified as CVE-2008-2375 represents a critical memory leak flaw within the vsftpd file transfer protocol daemon implementation on Red Hat Enterprise Linux systems. This issue specifically affects Red Hat Enterprise Linux versions 3 and 4, where the vsftpd service fails to properly manage memory allocation during authentication processes when PAM (Pluggable Authentication Modules) is enabled. The flaw manifests as a progressive memory consumption pattern that can ultimately lead to system instability and denial of service conditions. The vulnerability is particularly concerning because it operates through legitimate authentication mechanisms, making it difficult to distinguish between malicious attacks and normal system behavior.
The technical root cause of this vulnerability stems from improper memory management within the authentication handling code path of vsftpd. When remote attackers submit a large volume of invalid authentication attempts within a single session, the service fails to release allocated memory segments that are associated with these failed authentication requests. This memory leak occurs repeatedly with each failed authentication attempt, causing the process to consume increasing amounts of system memory over time. The vulnerability specifically leverages the PAM integration mechanism, which introduces additional complexity in memory allocation and cleanup operations during authentication cycles. This flaw operates at the application layer and can be exploited through network-based attacks targeting the FTP service port.
The operational impact of CVE-2008-2375 extends beyond simple resource exhaustion, creating cascading effects that can compromise system availability and stability. As memory consumption increases, the system may experience performance degradation, process scheduling delays, and eventually complete service unavailability. The vulnerability is particularly dangerous in production environments where continuous FTP service availability is critical, as attackers can effectively disable the service through sustained memory exhaustion attacks. Network administrators may observe gradual system slowdowns before complete service failure, making detection challenging and potentially allowing attackers to maintain persistent access while consuming resources. The vulnerability's exploitation requires minimal privileges and can be executed from any remote location with network access to the FTP service.
Mitigation strategies for this vulnerability should focus on immediate patching and system hardening measures. The most effective solution involves upgrading to vsftpd version 2.0.5 or later, which contains the necessary memory management fixes to prevent the leak during authentication failures. System administrators should also implement rate limiting mechanisms to restrict the number of authentication attempts per session and consider deploying intrusion detection systems to monitor for unusual authentication patterns. Network segmentation and firewall rules can help limit exposure by restricting access to FTP services to trusted networks only. Additionally, monitoring for memory consumption patterns and implementing automated alerts when memory usage exceeds predefined thresholds can help detect exploitation attempts before complete service failure occurs. This vulnerability aligns with CWE-401, which describes improper management of memory allocation and deallocation, and maps to ATT&CK technique T1499.004 for resource exhaustion attacks.