If su is compiled with PAM support, it is possible for any local user to send SIGKILL to other processes with root privileges. To exploit this, the user must be able to perform su with a successful login. This does NOT have to be the root user, even using su with the same id is enough, e.g. "su $(whoami)". SIGKILL can only be sent to processes which were executed after the su process. It is not possible to send SIGKILL to processes which were already running. Upstream patch in util-linux: https://github.com/karelzak/util-linux/commit/dffab154d29a288aa171ff50263ecc8f2e14a891
Acknowledgments: Name: Tobias Stöckmann
Created shadow-utils tracking bugs for this issue: Affects: fedora-all [bug 1425714]
Created util-linux tracking bugs for this issue: Affects: fedora-all [bug 1425713]
This issue has been addressed in the following products: Red Hat Enterprise Linux 6 Via RHSA-2017:0654 https://rhn.redhat.com/errata/RHSA-2017-0654.html
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2017:0907 https://access.redhat.com/errata/RHSA-2017:0907