A vulnerability has been identified in SIMATIC HMI Comfort Panels 4" - 22" (All versions < V15 Update 4), SIMATIC HMI Comfort Outdoor Panels 7" & 15" (All versions < V15 Update 4), SIMATIC HMI KTP Mobile Panels KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V15 Update 4), SIMATIC WinCC Runtime Advanced (All versions < V15 Update 4), SIMATIC WinCC Runtime Professional (All versions < V15 Update 4), SIMATIC WinCC (TIA Portal) (All versions < V15 Update 4), SIMATIC HMI Classic Devices (TP/MP/OP/MP Mobile Panel) (All versions). The webserver of affected HMI devices may allow URL redirections to untrusted websites. An attacker must trick a valid user who is authenticated to the device into clicking on a malicious link to exploit the vulnerability. At the time of advisory publication no public exploitation of this security vulnerability was known.