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 li
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | urllib3 | >= 1.17, < 1.18.1 | 1.18.1 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2016-9015
- https://github.com/urllib3/urllib3/commit/c32cdbc16a9634fa0f8c829d1270301570158715
- https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2017-98.yaml
- https://github.com/urllib3/urllib3
- https://web.archive.org/web/20210123184150/http://www.securityfocus.com/bid/93941
- http://www.openwall.com/lists/oss-security/2016/10/27/6
- http://www.securityfocus.com/bid/93941
- https://github.com/advisories/GHSA-v4w5-p2hg-8fh6
- CVSS vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N- Weakness (CWE)
CWE-295- Platform
- Python (PyPI)
- Package
urllib3- Disclosed
- 11.01.2017
- Updated
- 11.10.2026 12:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-v4w5-p2hg-8fh6 - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2017-98 - PyPA Advisory Database; CC BY 4.0
Vulnerability history: urllib3
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 22
- First → latest
- 01.2017 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 11
- Medium 10
Disclosures per year
- 2017: 1
- 2018: 1
- 2019: 2
- 2020: 2
- 2021: 2
- 2022: 0
- 2023: 3
- 2024: 1
- 2025: 4
- 2026: 6
-
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 li this entry
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