CVE-2021-28363: Fedoraproject Fedora

Medium severity, CVSS 6.5. EPSS: 2.1% chance of exploitation in the next 30 days.

The urllib3 library 1.26.x before 1.26.4 for Python omits SSL certificate validation in some cases involving HTTPS to HTTPS proxies. The initial connection to the HTTPS proxy (if an SSLContext isn't given via proxy_config) doesn't verify the hostname of the certificate. This means certificates for different servers that still validate properly with the default urllib3 SSLContext will be silently accepted.

Affected products

• Fedoraproject Fedora: version 34 only
• Oracle PeopleSoft Enterprise PeopleTools: version 8.59 only
• Python URLLIB3: from 1.26.0, before 1.26.4 (fixed in 1.26.4)

Published 2021-03-15. Last modified 2026-06-17.