A vulnerability has been identified in Totally Integrated Automation Portal (TIA Portal) V14 (All versions), Totally Integrated Automation Portal (TIA Portal) V15 (All versions), Totally Integrated Automation Portal (TIA Portal) V15.1 (All versions), Totally Integrated Automation Portal (TIA Portal) V16 (All versions), Totally Integrated Automation Portal (TIA Portal) V17 (All versions), Totally Integrated Automation Portal (TIA Portal) V18 (All versions), Totally Integrated Automation Portal (TIA Portal) V19 (All versions), Totally Integrated Automation Portal (TIA Portal) V20 (All versions). The know-how protection feature in affected products does not properly update the encryption of existing program blocks when a project file is updated. This could allow attackers with access to the project file to recover previous - yet unprotected - versions of the project without the knowledge of the know-how protection password.