SSL Certificate Validation Issue in urllib3 Library for Python
CVE-2021-28363

6.5MEDIUM

Key Information:

Vendor

Python

Status
Urllib3
Vendor
CVE Published:
15 March 2021

What is CVE-2021-28363?

The urllib3 library version 1.26.x prior to 1.26.4 for Python contains a vulnerability that affects SSL certificate validation when connecting to HTTPS proxies. When no SSLContext is provided in the proxy configuration, the library fails to verify the hostname against the SSL certificate, allowing potentially malicious certificates for different servers to be accepted without alerting the user. This oversight could lead to man-in-the-middle attacks as connections may be established with untrusted proxy servers.

References

https://github.com/urllib3/urllib3/commits/main
https://lists.fedoraproject.org/archives/list/package-ann...
vendor-advisory
https://security.gentoo.org/glsa/202107-36
vendor-advisory

CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.