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.
CVE-2016-9015
This low-severity CVE scores 3.7 under NVD CVSS v3. EPSS exploit probability: 0.0%, top 88% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 3.7
- EG Score
- 3.7(medium)
- EPSS
- 51.4%
- KEV
- Not listed
Published
January 11, 2017
Last Modified
May 6, 2026
References (4)
- cve@mitrehttp://www.openwall.com/lists/oss-security/2016/10/27/6
- cve@mitrehttp://www.securityfocus.com/bid/93941
- af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2016/10/27/6
- af854a3a-2127-422b-91ae-364da2661108http://www.securityfocus.com/bid/93941
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| urllib3 | 1.17, 1.18 | 1.18.1 | — |
Data Freshness Timeline
(refreshed 9× in last 7d / 39× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-11 08:24 UTCEPSS rescore
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- 2026-06-23 11:28 UTCOSV refresh
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- 2026-06-06 13:10 UTCOSV refresh
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- 2026-05-23 00:10 UTCEG score recompute
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- 2026-05-22 17:17 UTCEG score recompute
- 2026-05-20 22:37 UTCEPSS rescore
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