The urllib3 library before 1.24.2 for Python mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to use of the ssl_context, ca_certs, or ca_certs_dir argument.
https://github.com/urllib3/urllib3/compare/a6ec68a...1efadf4
http://www.openwall.com/lists/oss-security/2019/04/19/1
https://usn.ubuntu.com/3990-1/
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00039.html
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00041.html
https://access.redhat.com/errata/RHSA-2019:3335
https://access.redhat.com/errata/RHSA-2019:3590
https://lists.debian.org/debian-lts-announce/2021/06/msg00015.html
Source: MITRE
Published: 2019-04-18
Updated: 2021-06-15
Type: CWE-295
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:P/A:N
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH