A vulnerability was found in postgresql versions 11.x prior to 11.3. The Windows installer for BigSQL-supplied PostgreSQL does not lock down the ACL of the binary installation directory or the ACL of the data directory; it keeps the inherited ACL. In the default configuration, an attacker having both an unprivileged Windows account and an unprivileged PostgreSQL account can cause the PostgreSQL service account to execute arbitrary code. An attacker having only the unprivileged Windows account can read arbitrary data directory files, essentially bypassing database-imposed read access limitations. An attacker having only the unprivileged Windows account can also delete certain data directory files.