In GNU patch through 2.7.6, the following of symlinks is mishandled in certain cases other than input files. This affects inp.c and util.c.
https://www.debian.org/security/2019/dsa-4489
https://usn.ubuntu.com/4071-2/
https://usn.ubuntu.com/4071-1/
https://security.netapp.com/advisory/ntap-20190828-0001/
https://security.gentoo.org/glsa/201908-22
https://seclists.org/bugtraq/2019/Jul/54
https://seclists.org/bugtraq/2019/Aug/29
https://lists.debian.org/debian-lts-announce/2019/07/msg00016.html
https://github.com/irsl/gnu-patch-vulnerabilities
https://git.savannah.gnu.org/cgit/patch.git/commit/?id=dce4683cbbe107a95f1f0d45fabc304acfb5d71a
http://packetstormsecurity.com/files/154124/GNU-patch-Command-Injection-Directory-Traversal.html