Babel.Locale in Babel before 2.9.1 allows attackers to load arbitrary locale .dat files (containing serialized Python objects) via directory traversal, leading to code execution.
https://www.tenable.com/security/research/tra-2021-14
https://www.debian.org/security/2021/dsa-5018
https://lists.debian.org/debian-lts/2021/10/msg00040.html
https://lists.debian.org/debian-lts-announce/2021/10/msg00018.html