SIMATIC STEP 7 and PCS 7 contain a database management system that could allow remote users to use embedded functions of the database (local or in a network share) that have impact on the server.
An attacker with network access to the server network could leverage these embedded functions to run code in the database management system’s server (where STEP 7 or PCS 7 are running).
Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where fixes are not, or not yet available.
https://cert-portal.siemens.com/productcert/html/ssa-968170.html