Double free issue exists in Kostac PLC Programming Software Version 1.6.11.0 and earlier. Arbitrary code may be executed by having a user open a specially crafted project file which was saved using Kostac PLC Programming Software Version 1.6.9.0 and earlier because the issue exists in parsing of KPP project files. The vendor states that Kostac PLC Programming Software Version 1.6.10.0 or later implements the function which prevents a project file alteration. Therefore, to mitigate the impact of these vulnerabilities, a project file which was saved using Kostac PLC Programming Software Version 1.6.9.0 and earlier needs to be saved again using Kostac PLC Programming Software Version 1.6.10.0 or later.