CVE-2021-32837: mechanize, a library for automatically interacting with HTTP web servers, contains a regular expression that i

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HIGH 7.5REMOTEUPGRADE

CVE-2021-32837 is a high-severity flaw (CVSS 7.5) affecting mechanize. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

mechanize, a library for automatically interacting with HTTP web servers, contains a regular expression that is vulnerable to regular expression denial of service (ReDoS) prior to version 0.4.6. If a web server responds in a malicious way, then mechanize could crash. Version 0.4.6 has a patch for the issue.

Why this priority

High severity
EPSS top 2%: very likely to be exploited
Public exploit reference
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	28.9% (top 2%)
CISA exploited list	No
Weakness	CWE-1333
Published	2023-01-17
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: mechanize project

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

Am I affected?

Timeline

2023-01-17 22:15 UTCPublished CVE record published
2026-06-17 03:53 UTCUpdated Record last modified

mechanize project mechanize UPGRADE

Affected: < 0.4.6

Fixed in: 0.4.6

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show mechanize

2. UPGRADE to 0.4.6

pip install --upgrade "mechanize>=0.4.6"

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-2021-32837?

mechanize: upgrade to 0.4.6. Exact commands for each OS are on this page.

Is CVE-2021-32837 being exploited?

CVE-2021-32837 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-2021-32837 affect?

CVE-2021-32837 affects mechanize. Severity is high (CVSS 7.5). mechanize, a library for automatically interacting with HTTP web servers, contains a regular expression that is vulnerable to regular expression denial of service (ReDoS) prior to version 0.4.6. If a web server responds in a malicious way,

How urgent is CVE-2021-32837?

Priority 61/100. High severity; EPSS top 2%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-31033 MEDIUM 5.9 UPGRADE MITIGATE The Mechanize library is used for automating interaction with websites

References

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