---
id: CVE-2021-32838
aliases:
  - GHSA-3q6g-vf58-7m4g
  - PYSEC-2021-325
title: Regular Expression Denial of Service in flask-restx
summary: Regular Expression Denial of Service in flask-restx
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: flask-restx
product: flask-restx
ecosystem: pip
affected:
  - flask-restx < 0.5.1
patched:
  - flask-restx 0.5.1
published: '2021-09-08'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-3q6g-vf58-7m4g'
references:
  - url: >-
      https://github.com/python-restx/flask-restx/security/advisories/GHSA-3q6g-vf58-7m4g
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2021-32838'
  - url: 'https://github.com/python-restx/flask-restx/issues/372'
  - url: >-
      https://github.com/python-restx/flask-restx/commit/bab31e085f355dd73858fd3715f7ed71849656da
  - url: 'https://github.com/advisories/GHSA-3q6g-vf58-7m4g'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/flask-restx/PYSEC-2021-325.yaml
  - url: 'https://github.com/python-restx/flask-restx'
  - url: >-
      https://github.com/python-restx/flask-restx/blob/fd99fe11a88531f5f3441a278f7020589f9d2cc0/flask_restx/inputs.py#L51
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5UCTFVDU3677B5OBGK4EF5NMUPJLL6SQ
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QUD6SWZLX52AAZUHDETJ2CDMQGEPGFL3
  - url: 'https://pypi.org/project/flask-restx'
tags:
  - osv
  - pip
epss: 0.01864
epssPercentile: 0.78384
ingestedAt: '2026-07-08T18:25:44.940Z'
---

## Overview

Flask RESTX contains a regular expression that is vulnerable to [ReDoS](https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS) (Regular Expression Denial of Service) in `email_regex`.


## Affected packages

- `flask-restx < 0.5.1`

## Remediation

Upgrade to a patched release:

- `flask-restx 0.5.1`