CVE-2015-8762 in FreeRADIUS
Summary
by MITRE
The EAP-PWD module in FreeRADIUS 3.0 through 3.0.8 allows remote attackers to cause a denial of service (NULL pointer dereference and server crash) via a zero-length EAP-PWD packet.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 03/04/2025
The vulnerability identified as CVE-2015-8762 represents a critical denial of service weakness within the EAP-PWD module of FreeRADIUS versions 3.0 through 3.0.8. This issue manifests when the system processes malformed EAP-PWD packets containing zero-length data, leading to a null pointer dereference condition that ultimately causes the FreeRADIUS server to crash. The vulnerability operates at the authentication layer of the RADIUS protocol, specifically targeting the Extensible Authentication Protocol with Password (EAP-PWD) implementation that provides secure password-based authentication mechanisms for network access.
The technical flaw stems from inadequate input validation within the EAP-PWD module's packet processing logic. When a zero-length EAP-PWD packet is received, the module fails to properly handle this edge case and attempts to dereference a null pointer during packet parsing operations. This null pointer dereference represents a classic software bug pattern that aligns with CWE-476, which specifically addresses null pointer dereference vulnerabilities. The vulnerability exists because the developers did not implement proper bounds checking or null validation before attempting to access memory locations that may not have been properly initialized or allocated.
The operational impact of this vulnerability extends beyond simple service disruption as it enables remote attackers to systematically crash FreeRADIUS servers without requiring authentication or specialized privileges. This makes the vulnerability particularly dangerous in network environments where RADIUS servers serve as critical infrastructure components for wireless network access, VPN authentication, and network device access control. The denial of service condition affects the availability of network authentication services, potentially disrupting legitimate user access and creating security gaps in network access control. Attackers can exploit this vulnerability by simply sending a specially crafted zero-length EAP-PWD packet to the target server, making the attack vector both simple and highly effective.
Mitigation strategies for CVE-2015-8762 primarily involve upgrading to FreeRADIUS version 3.0.9 or later, where the vulnerability has been addressed through proper input validation and null pointer checks. System administrators should also implement network segmentation and access controls to limit exposure of vulnerable FreeRADIUS servers to untrusted networks. Network monitoring solutions should be configured to detect anomalous EAP-PWD packet patterns and trigger alerts when zero-length packets are observed. Additionally, implementing rate limiting and packet filtering rules at network boundaries can help reduce the effectiveness of potential exploitation attempts while maintaining legitimate network functionality. This vulnerability demonstrates the importance of proper input validation and robust error handling in authentication systems, as outlined in the ATT&CK framework's defensive techniques related to input validation and process injection prevention. The issue highlights the critical need for thorough testing of edge cases in authentication protocols and emphasizes that even seemingly benign malformed packets can lead to complete system compromise through denial of service attacks.