CVE-2021-33026

DISPUTED The Flask-Caching extension through 1.10.1 for Flask relies
on Pickle for serialization, which may lead to remote code execution or
local privilege escalation. If an attacker gains access to cache storage
(e.g., filesystem, Memcached, Redis, etc.), they can construct a crafted
payload, poison the cache, and execute Python code. NOTE: a third party
indicates that exploitation is extremely unlikely unless the machine is
already compromised; in other cases, the attacker would be unable to write
their payload to the cache and generate the required collision.