Sandboxed app can't listen on a high-numbered port

We have an application that binds a TCP socket on port 5000 for listening. It works fine outside of a sandbox. When we put the app into a sandbox we get the following error:

Aug  9 16:14:30 swi-mdm9x40 user.err Legato: =ERR= | swTalker[22085]/demoComponent T=main | demo.c _demoComponent_COMPONENT_INIT() 1534 | creating socket failed: Permission denied

Version information:

root@swi-mdm9x40:~# legato version

Try creating a group with gid 3003 and making your app a member of that group.