Medium severity · published Mar 15, 2021
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
6.5
CVSS
2.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)2.2% · higher than 82% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FE
Fedora · Fedoraproject
34 · source: NVD
PE
Peoplesoft Enterprise Peopletools · Oracle
8.59 · source: NVD
UR
Urllib3 · Python
1.26.0 before 1.26.4 · source: NVD
SS
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.0 before V3.1.5; V3.1.0 before V3.1.5 · source: CISA
SS
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP · Siemens
V3.1.0 before V3.1.5; V3.1.0 before V3.1.5 · source: CISA
SS
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.0 before V3.1.5 · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-28363
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-28363
Patch
https://github.com/urllib3/urllib3/commit/8d65ea1ecf6e2cdc27d42124e587c1b83a3118b0
Patch
https://github.com/urllib3/urllib3/commits/main
Mitigation
https://github.com/urllib3/urllib3/security/advisories/GHSA-5phf-pp7p-vc2r
lists.fedoraproject.org
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4S65ZQVZ2ODGB52IC7VJDBUK4M5INCXL/
Third Party Advisory
https://pypi.org/project/urllib3/1.26.4/
Third Party Advisory
https://security.gentoo.org/glsa/202107-36
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