A vulnerability exists in affected products that could allow remote attackers to affect the availability of the devices under certain conditions.
The underlying TCP stack can be forced to make very computation expensive calls for every incoming packet which can lead to a Denial-of-Service.
Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fix versions and recommends countermeasures for products where fixes are not, or not yet available.

https://cert-portal.siemens.com/productcert/html/ssa-593272.html