popd in bash might allow local users to bypass the restricted shell and cause a use-after-free via a crafted address.
https://security.gentoo.org/glsa/201701-02
https://lists.debian.org/debian-lts-announce/2019/03/msg00028.html
https://access.redhat.com/errata/RHSA-2017:1931
http://www.securityfocus.com/bid/94398
http://www.openwall.com/lists/oss-security/2016/11/17/9