Security advisory
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2016-9015
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 06:20 UTC · Revision 1
Source evidence
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.
osv:CVE-2016-9015
Complete source record
{
"id": "a001af57dba6b5a8d8935cbf2665ce70a088da4ad1ced005b84878116f43b080",
"url": "https://osv.dev/vulnerability/CVE-2016-9015",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2016-9015",
"summary": "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.",
"evidence": "osv:CVE-2016-9015",
"products": [],
"severity": "low",
"structured": {
"id": "CVE-2016-9015",
"aliases": [
"CVE-2016-9015",
"GHSA-v4w5-p2hg-8fh6",
"PYSEC-2017-98"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/urllib3/urllib3",
"type": "GIT",
"events": [
{
"introduced": "a8948b82f1a54c8f5ffabb01c52f2098785013a2"
},
{
"last_affected": "7d01b990cf77b33659e562189e6962862b292170"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:python:urllib3:1.17:*:*:*:*:*:*:*",
"range": [
{
"introduced": "1.17"
},
{
"last_affected": "1.17"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:python:urllib3:1.18:*:*:*:*:*:*:*",
"range": [
{
"introduced": "1.18"
},
{
"last_affected": "1.18"
}
],
"source": "CPE_STRING"
}
]
}
}
],
"versions": [
"1.17",
"1.18"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2016-9015.json"
}
}
],
"modified": "2026-10-24T10:30:38.131894746Z",
"provider": "osv",
"references": [],
"provider_metadata": {}
},
"related_cves": [
{
"value": "CVE-2016-9015",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 434371,
"published_at": "2017-01-11T16:59:00.347+00:00"
}