CVE-2017-12172 in PostgreSQL
Summary
by MITRE
PostgreSQL 10.x before 10.1, 9.6.x before 9.6.6, 9.5.x before 9.5.10, 9.4.x before 9.4.15, 9.3.x before 9.3.20, and 9.2.x before 9.2.24 runs under a non-root operating system account, and database superusers have effective ability to run arbitrary code under that system account. PostgreSQL provides a script for starting the database server during system boot. Packages of PostgreSQL for many operating systems provide their own, packager-authored startup implementations. Several implementations use a log file name that the database superuser can replace with a symbolic link. As root, they open(), chmod() and/or chown() this log file name. This often suffices for the database superuser to escalate to root privileges when root starts the server.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/02/2025
This vulnerability represents a critical privilege escalation flaw in PostgreSQL database systems affecting multiple major versions including 10.x before 10.1, 9.6.x before 9.6.6, 9.5.x before 9.5.10, 9.4.x before 9.4.15, 9.3.x before 9.3.20, and 9.2.x before 9.2.24. The issue stems from the database server's startup process where the system operates under a non-root account but database superusers possess the capability to execute arbitrary code under that same system account. This vulnerability aligns with CWE-276, which addresses improper privileges and access control issues in software systems. The flaw specifically exploits the interaction between the PostgreSQL startup scripts and file system permissions during system boot processes.
The technical exploitation mechanism involves the database superuser manipulating log file names that are used during the server startup sequence. When the system starts PostgreSQL, the startup process opens, chmods, or chowns log files using names that can be controlled by the superuser through symbolic link manipulation. This creates a race condition and privilege escalation opportunity where the database superuser can effectively gain root privileges when the server starts up under root account context. The vulnerability demonstrates a classic case of insecure file handling during system initialization processes and represents a serious violation of the principle of least privilege. The attack vector is particularly dangerous because it leverages legitimate system startup procedures to achieve unauthorized privilege escalation.
The operational impact of this vulnerability is severe and far-reaching for organizations using affected PostgreSQL versions. Database superusers can escalate their privileges to root level access, potentially allowing them to execute arbitrary code with system-level privileges, modify system files, install malware, or access sensitive data across the entire system. This vulnerability affects systems where PostgreSQL is configured to start automatically during boot processes, making it particularly dangerous in enterprise environments where database administrators often possess superuser privileges. The vulnerability can be exploited without requiring special authentication credentials beyond database superuser access, and the exploitation is relatively straightforward once the attacker has database superuser privileges. This flaw can be classified under ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' and specifically addresses local privilege escalation attacks.
Organizations should implement immediate mitigations including upgrading to patched versions of PostgreSQL, reviewing and hardening startup script implementations to prevent symbolic link manipulation, and ensuring that database superuser privileges are strictly controlled and monitored. System administrators should audit their PostgreSQL installations for vulnerable startup scripts and consider implementing additional security measures such as file system permissions hardening, regular security audits, and monitoring for unauthorized privilege escalation attempts. The vulnerability highlights the importance of secure coding practices during system initialization and proper privilege separation between database operations and system-level processes. Additionally, organizations should consider implementing network segmentation and access controls to limit the potential impact of such privilege escalation attacks and should regularly update their security monitoring systems to detect suspicious activities related to database superuser privileges.