Timescale TimescaleDB 1.x and 2.x before 2.5.2 may allow privilege escalation during extension installation. The installation process uses commands such as CREATE x IF NOT EXIST that allow an unprivileged user to precreate objects. These objects will be used by the installer (which executes as Superuser), leading to privilege escalation. In order to be able to take advantage of this, an unprivileged user would need to be able to create objects in a database and then get a Superuser to install TimescaleDB into their database. (In the fixed versions, the installation aborts when it finds that an object already exists.)
https://github.com/timescale/timescaledb/security/advisories/GHSA-fh8v-663w-79w9
https://github.com/timescale/timescaledb/commit/c8b8516e466c2bb7d2ae6a4b0b2e8e60b24b24a2
https://github.com/timescale/timescaledb/commit/6275c2985927cfd4900b85cac5120227c8cb1f0c
https://docs.timescale.com/timescaledb/latest/overview/release-notes/