CVE-2021-32838: Flask-RESTX (pypi package flask-restx) is a community driven fork of Flask-RESTPlus

This month

HIGH 7.5REMOTEUPGRADEMITIGATE

CVE-2021-32838 is a high-severity flaw (CVSS 7.5) affecting flask-restx, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.9% (top 21%)
CISA exploited list	No
Weakness	CWE-400
Published	2021-09-20
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: fedoraproject · flask-restx project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-09-20 18:15 UTCPublished CVE record published
2026-06-17 03:53 UTCUpdated Record last modified

flask-restx project flask-restx UPGRADE

Affected: < 0.5.1

Fixed in: 0.5.1

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show flask-restx

2. UPGRADE to 0.5.1

pip install --upgrade "flask-restx>=0.5.1"

fedoraproject fedora MITIGATE

Affected: 33 · 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 33

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-32838?

flask-restx: upgrade to 0.5.1; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-32838 being exploited?

CVE-2021-32838 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-32838 affect?

CVE-2021-32838 affects flask-restx, fedora. Severity is high (CVSS 7.5). 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.

How urgent is CVE-2021-32838?

Priority 51/100. High severity; Remotely exploitable, no login, no user action

Software pages

PyPI packages vulnerabilities · Flask vulnerabilities

References

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