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.
github.com/advisories/GHSA-3q6g-vf58-7m4g
github.com/python-restx/flask-restx/blob/fd99fe11a88531f5f3441a278f7020589f9d2cc0/flask_restx/inputs.py#L51
github.com/python-restx/flask-restx/commit/bab31e085f355dd73858fd3715f7ed71849656da
github.com/python-restx/flask-restx/issues/372
pypi.org/project/flask-restx/