Smarty before 3.1.39 allows code injection via an unexpected function name after a {function name= substring.
https://www.debian.org/security/2022/dsa-5151
https://security.gentoo.org/glsa/202105-06
https://lists.debian.org/debian-lts-announce/2021/04/msg00014.html
https://lists.debian.org/debian-lts-announce/2021/04/msg00004.html
https://github.com/smarty-php/smarty/blob/master/CHANGELOG.md