Andreas Beckmann debian reports:

openvswitch-pki creates the following world writable directories during
installation:

    drwx-wx-wx 2 root root 40 Aug  1 05:32 /var/lib/openvswitch/pki/controllerca/incoming
    drwx-wx-wx 2 root root 40 Aug  1 05:32 /var/lib/openvswitch/pki/switchca/incoming

Even if an ordinary local user cannot list the contents of the
directory, he may correctly derive/guess filenames (unless they are
exclusively $(mktemp)) and delete and replace files in there.

I don't know how openvswitch-pki works, how it uses this directory,
what probelms could possibly arise out of this.

References: 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=683665

Please note on Fedora 16 and 17 run the command:

/usr/bin/ovs-pki --force init

to create the directories.