A flaw was found in GNU Coreutils through 8.29 in chown-core.c. The functions chown and chgrp do not prevent replacement of a plain file with a symlink during use of the POSIX "-R -L" options, which allows local users to modify the ownership of arbitrary files by leveraging a race condition (CVE-2017-18018).
A flaw was found in Gnulib before 2018-09-23. The converttodecimal function in vasnprintf.c has a heap-based buffer overflow because memory is not allocated for a trailing '\0' character during %f processing (CVE-2018-17942).