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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2017-12172
• https://access.redhat.com/errata/RHSA-2017:3402
• https://access.redhat.com/errata/RHSA-2017:3403
• https://access.redhat.com/errata/RHSA-2017:3404
• https://access.redhat.com/errata/RHSA-2017:3405
• https://www.postgresql.org/about/news/1801/
• https://www.postgresql.org/support/security/
• http://www.securityfocus.com/bid/101949
• http://www.securitytracker.com/id/1039752