CVE-2021-28363
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.
- Score
- CVSS 3.1 6.5 Medium
- Status
- Modified - cve@mitre.org
- Published
- 2021-03-15
- Last modified
- 2026-10-14
- Weaknesses
- CWE-295
Affected products
- Fedora (Fedoraproject)
- Peoplesoft Enterprise Peopletools (Oracle)
- Urllib3 (Python)
- Simatic S7-1500 Cpu 1518-4 Pndp Mfp (Siemens)
- Simatic S7-1500 Cpu 1518f-4 Pndp Mfp (Siemens)
- Siplus S7-1500 Cpu 1518-4 Pndp Mfp (Siemens)
References
- https://github.com/urllib3/urllib3/commits/main
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4S65ZQVZ2ODGB52IC7VJDB…
- https://security.gentoo.org/glsa/202107-36
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://pypi.org/project/urllib3/1.26.4/
- https://github.com/urllib3/urllib3/commit/8d65ea1ecf6e2cdc27d42124e587c1b83a3118b0
- https://github.com/urllib3/urllib3/security/advisories/GHSA-5phf-pp7p-vc2r
- https://security.gentoo.org/glsa/202305-02
- https://security.netapp.com/advisory/ntap-20240621-0007/
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html
