CVE-2019-10143 in FreeRADIUS
Summary
by MITRE
It was discovered freeradius up to and including version 3.0.19 does not correctly configure logrotate, allowing a local attacker who already has control of the radiusd user to escalate his privileges to root, by tricking logrotate into writing a radiusd-writable file to a directory normally inaccessible by the radiusd user.
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Analysis
by VulDB Data Team • 01/20/2026
The vulnerability CVE-2019-10143 represents a critical privilege escalation flaw in FreeRADIUS versions up to and including 3.0.19 that demonstrates how inadequate log rotation configuration can lead to severe system compromise. This issue specifically targets the interaction between the radiusd service and the logrotate utility, creating an exploitable condition that allows local attackers with existing radiusd user access to escalate their privileges to the root level. The flaw exploits a fundamental misconfiguration in how logrotate handles file permissions and directory access controls when processing FreeRADIUS log files, fundamentally undermining the principle of least privilege that should protect system integrity.
The technical implementation of this vulnerability stems from FreeRADIUS's improper configuration of logrotate directives that govern how log files are rotated and managed. When logrotate executes, it processes the radiusd log files and creates or modifies files in directories that typically require elevated privileges to access. The vulnerability occurs because the radiusd user, while having access to write to log files, can manipulate the logrotate process to write files to locations where they normally lack permissions. This creates a scenario where the radiusd user can influence the logrotate process to create or modify files in system directories that should be restricted to root access, effectively bypassing normal access controls through a carefully crafted attack vector.
The operational impact of CVE-2019-10143 extends beyond simple privilege escalation as it provides attackers with a persistent foothold in the system that can be leveraged for further exploitation. Once escalated to root privileges, attackers can modify system binaries, establish backdoors, access sensitive data, and potentially compromise the entire network infrastructure that relies on FreeRADIUS for authentication services. This vulnerability is particularly dangerous because it requires minimal initial access - only the ability to execute commands as the radiusd user, which may already be achievable through other means such as weak authentication or compromised service accounts. The attack vector demonstrates how seemingly innocuous system utilities like logrotate can become critical attack surfaces when misconfigured.
The exploitation of this vulnerability aligns with several tactics outlined in the MITRE ATT&CK framework, particularly focusing on privilege escalation techniques and the abuse of system utilities for malicious purposes. This flaw can be classified under CWE-276, which addresses improper permissions for system resources, and CWE-732, which covers inadequate permissions for system resources. The vulnerability represents a classic case of privilege escalation through misconfigured system utilities, where the attacker leverages legitimate system functionality to achieve unauthorized access. Organizations running FreeRADIUS versions 3.0.19 or earlier face significant risk as this vulnerability can be exploited without requiring additional attack vectors, making it a high-priority target for remediation.
Mitigation strategies for CVE-2019-10143 primarily involve upgrading to FreeRADIUS version 3.0.20 or later, which contains the necessary fixes for the logrotate configuration. System administrators should also review and tighten the logrotate configuration for FreeRADIUS to ensure that log files are properly secured and that the rotation process does not create opportunities for privilege escalation. Additional protective measures include implementing proper file system permissions, monitoring logrotate processes for unusual activity, and conducting regular security audits of system utilities that handle log management. The vulnerability underscores the importance of comprehensive security reviews of system configuration files and the critical need for proper access control mechanisms that prevent local users from manipulating system services that have elevated privileges.