Flask-RESTX (pypi package flask-restx) is a community driven fork of Flask-RESTPlus. Flask-RESTX before version 0.5.1 is vulnerable to ReDoS (Regular Expression Denial of Service) in email_regex. This is fixed in version 0.5.1.
"https://github.com/pypa/advisory-database/blob/main/vulns/flask-restx/PYSEC-2021-325.yaml"