CVE-2016-9015
Versions 1.17 and 1.18 of the Python urllib3 library suffer from a vulnerability that can cause them, in certain configurations, to not correctly validate TLS certificates.
Does this matter?
Lower severity and a low EPSS score (0.75%). Track it; it rarely justifies an emergency change on its own.
Description
Versions 1.17 and 1.18 of the Python urllib3 library suffer from a vulnerability that can cause them, in certain configurations, to not correctly validate TLS certificates. This places users of the library with those configurations at risk of man-in-the-middle and information leakage attacks. This vulnerability affects users using versions 1.17 and 1.18 of the urllib3 library, who are using the optional PyOpenSSL support for TLS instead of the regular standard library TLS backend, and who are using OpenSSL 1.1.0 via PyOpenSSL. This is an extremely uncommon configuration, so the security impact of this vulnerability is low.
- CVSS 3.0
- 3.7 LOWCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- EPSS
- 0.75% probability · 55th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-295
- Affected
- python/urllib3
- Source
- cve@mitre.org
EPSS 0.8% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.openwall.com/lists/oss-security/2016/10/27/6Mailing List, Mitigation
- http://www.securityfocus.com/bid/93941Third Party Advisory, VDB Entry
- http://www.openwall.com/lists/oss-security/2016/10/27/6Mailing List, Mitigation
- http://www.securityfocus.com/bid/93941Third Party Advisory, VDB Entry
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.