The cache action in action/cache.py in MoinMoin through 1.9.10 allows directory traversal through a crafted HTTP request. An attacker who can upload attachments to the wiki can use this to achieve remote code execution.
https://www.debian.org/security/2020/dsa-4787
https://lists.debian.org/debian-lts-announce/2020/11/msg00020.html
https://github.com/moinwiki/moin-1.9/security/advisories/GHSA-52q8-877j-gghq