Several SIMATIC S7-1500 and S7-1200 CPU versions are affected by an open redirect vulnerability that could allow an attacker to make the web server of affected devices redirect a legitimate user to an attacker-chosen URL. For a successful attack, the legitimate user must actively click on an attacker-crafted link.
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 specific countermeasures for products where fixes are not, or not yet available.

https://cert-portal.siemens.com/productcert/html/ssa-876787.html