KioWare for Windows (versions all through 8.34) allows to escape the environment by downloading PDF files, which then by default are opened in an external PDF viewer. By using built-in functions of that viewer it is possible to launch a web browser, search through local files and, subsequently, launch any program with user privileges.
Exploitability
AV:LAC:LPR:NUI:NScope
S:UImpact
C:HI:HA:H8.4/CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HOther