Impact

Users who are using an HTTPS proxy to issue HTTPS requests and haven't configured their own SSLContext via proxy_config.
Only the default SSLContext is impacted.

Patches

urllib3 >=1.26.4 has the issue resolved. urllib3<1.26 is not impacted due to not supporting HTTPS requests via HTTPS proxies.

Workarounds

Upgrading is recommended as this is a minor release and not likely to break current usage.

Configuring an SSLContext with check_hostname=True and passing via proxy_config instead of relying on the default SSLContext

For more information

If you have any questions or comments about this advisory:

• Email us at [email protected]

References

• GHSA-5phf-pp7p-vc2r
• https://nvd.nist.gov/vuln/detail/CVE-2021-28363
• urllib3/urllib3@8d65ea1
• https://github.com/urllib3/urllib3/releases/tag/1.26.4
• https://github.com/urllib3/urllib3/commits/main
• https://github.com/urllib3/urllib3/blob/main/CHANGES.rst#1264-2021-03-15
• https://security.gentoo.org/glsa/202107-36
• https://www.oracle.com/security-alerts/cpuoct2021.html
• https://github.com/pypa/advisory-db/tree/main/vulns/urllib3/PYSEC-2021-59.yaml
• https://security.gentoo.org/glsa/202305-02
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4S65ZQVZ2ODGB52IC7VJDBUK4M5INCXL
• https://lists.fedoraproject.org/archives/list/[email protected]/message/4S65ZQVZ2ODGB52IC7VJDBUK4M5INCXL
• https://pypi.org/project/urllib3/1.26.4
• https://security.netapp.com/advisory/ntap-20240621-0007