CVE-2016-9015

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Summary

CVECVE-2016-9015
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2017-01-11 16:59:00 UTC
Updated2026-05-06 22:30:45 UTC
DescriptionVersions 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.

Risk And Classification

Primary CVSS: v3.0 3.7 LOW from [email protected]

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS: 0.000380000 probability, percentile 0.113370000 (date 2026-05-11)

Problem Types: CWE-295 | n/a

VersionSourceTypeScoreSeverityVector
3.0[email protected]Primary3.7LOWCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
2.0[email protected]Primary2.6AV:N/AC:H/Au:N/C:P/I:N/A:N

CVSS v3.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v2.0 Breakdown

Access Vector
Network
Access Complexity
High
Authentication
None
Confidentiality
Partial
Integrity
None
Availability
None

AV:N/AC:H/Au:N/C:P/I:N/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Python Urllib3 1.17 All All All
Application Python Urllib3 1.18 All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na N/a affected n/a Not specified

References

ReferenceSourceLinkTags
Python urllib3 CVE-2016-9015 TLS Certificate Validation Security Bypass Vulnerability af854a3a-2127-422b-91ae-364da2661108 www.securityfocus.com Third Party Advisory, VDB Entry
oss-security - CVE-2016-9015: Python urllib3 1.17 and 1.18 certificate verification failure af854a3a-2127-422b-91ae-364da2661108 www.openwall.com Mailing List, Mitigation
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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