CVE-2016-1255 in postgresql-common
Summary
by MITRE
The pg_ctlcluster script in postgresql-common package in Debian wheezy before 134wheezy5, in Debian jessie before 165+deb8u2, in Debian unstable before 178, in Ubuntu 12.04 LTS before 129ubuntu1.2, in Ubuntu 14.04 LTS before 154ubuntu1.1, in Ubuntu 16.04 LTS before 173ubuntu0.1, in Ubuntu 17.04 before 179ubuntu0.1, and in Ubuntu 17.10 before 184ubuntu1.1 allows local users to gain root privileges via a symlink attack on a logfile in /var/log/postgresql.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/02/2025
The vulnerability described in CVE-2016-1255 represents a critical privilege escalation flaw within the postgresql-common package ecosystem on Debian and Ubuntu systems. This issue specifically targets the pg_ctlcluster script which serves as a crucial component for managing postgresql cluster operations across different system states. The vulnerability arises from improper handling of log file creation and management within the /var/log/postgresql directory, creating an exploitable race condition that allows local attackers to elevate their privileges to root level access. The flaw affects multiple Debian and Ubuntu releases spanning from the wheezy to the unstable releases, indicating a widespread impact across the package ecosystem and highlighting the severity of the underlying design flaw.
The technical mechanism behind this vulnerability operates through a classic symlink attack pattern that exploits the insecure creation of log files. When the pg_ctlcluster script executes, it creates log files in the /var/log/postgresql directory without proper validation of existing symbolic links. An attacker can manipulate this process by pre-creating symbolic links in the target directory that point to sensitive system files such as /etc/shadow or /etc/passwd. During the normal operation of the postgresql service management, the script creates log entries that are written to these maliciously crafted symbolic links, effectively allowing the attacker to write arbitrary data to privileged files. This type of vulnerability falls under the CWE-377 weakness category, specifically CWE-377: Insecure Temporary File, which is further classified under the broader category of CWE-276: Incorrect Permission Assignment for Critical Resources. The attack vector is particularly insidious because it leverages the legitimate system management operations to achieve unauthorized privilege escalation.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over the affected system. Once root privileges are gained, attackers can modify system configurations, install persistent backdoors, exfiltrate sensitive data, or establish covert access channels that persist across system reboots. The vulnerability affects systems running various versions of Debian and Ubuntu that utilize the postgresql-common package, making it particularly dangerous for server environments where postgresql is commonly deployed. Organizations running these affected versions face significant risk as the attack requires minimal privileges and can be executed by any local user, potentially allowing attackers to compromise entire server infrastructures. The vulnerability's presence in long-term support releases such as Ubuntu 12.04 LTS and 14.04 LTS makes it particularly concerning for enterprise environments where patching cycles may be extended.
Mitigation strategies for CVE-2016-1255 primarily involve immediate patching of affected systems with the vendor-provided security updates that address the insecure file creation patterns. System administrators should also implement additional security controls such as restricting write permissions on the /var/log/postgresql directory and monitoring for suspicious symbolic link creation patterns. The ATT&CK framework categorizes this vulnerability under T1068: Exploitation for Privilege Escalation, specifically targeting the technique of T1068.1: Exploitation for Privilege Escalation using Local Privilege Escalation techniques. Organizations should conduct comprehensive vulnerability assessments to identify all systems running affected versions of postgresql-common and implement proper system hardening measures including regular security audits and monitoring for unauthorized file system modifications. Additionally, implementing principle of least privilege access controls and ensuring that only authorized users have access to postgresql management operations can significantly reduce the attack surface for this particular vulnerability.