util-linux/mdev.c in BusyBox before 1.21.0 uses 0777 permissions for parent directories when creating nested directories under /dev/, which allows local users to have unknown impact and attack vectors.
https://support.t-mobile.com/docs/DOC-21994
https://seclists.org/bugtraq/2019/Jun/14
https://euvd.enisa.europa.eu/vulnerability/EUVD-2013-1833
http://seclists.org/fulldisclosure/2020/Mar/15
http://seclists.org/fulldisclosure/2020/Aug/20
http://seclists.org/fulldisclosure/2019/Jun/18
http://rhn.redhat.com/errata/RHSA-2013-1732.html
http://lists.busybox.net/pipermail/busybox/2013-January/078864.html
http://git.busybox.net/busybox/commit/?id=4609f477c7e043a4f6147dfe6e86b775da2ef784