CVE-2021-28363The urllib3 library 1.26.x before 1.26.4 for Python omits SSL certificate validation in some cases involving HTTPS to HTTPS proxies.
Updated under an hour ago ()
Does this affect you?
It affects Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP and 5 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
The urllib3 library 1.26.x before 1.26.4 for Python omits SSL certificate validation in some cases involving HTTPS to HTTPS proxies. The initial connection to the HTTPS proxy (if an SSLContext isn't given via proxy_config) doesn't verify the hostname of the certificate. This means certificates for different servers that still validate properly with the default urllib3 SSLContext will be silently accepted.
- CVSS
- 6.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- mitre
- NVD analysis
- Modified
- Record last updated
- Oct 14, 2026
- First seen by InfoSec Signals
- Oct 14, 2026
Affected products
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.0 before V3.1.5 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.0 before V3.1.5 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.0 before V3.1.5 | CISA ADP |
python urllib3 python:urllib3 | from 1.26.0 before 1.26.4 | NVD |
fedoraproject fedora fedoraproject:fedora | 34 | NVD |
oracle peoplesoft_enterprise_peopletools oracle:peoplesoft_enterprise_peopletools | 8.59 | NVD |
References
- https://github.com/urllib3/urllib3/commits/mainpatch, third-party-advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4S65ZQVZ2ODGB52IC7VJDBUK4M5INCXL/vendor-advisory
- https://security.gentoo.org/glsa/202107-36vendor-advisory, third-party-advisory
- https://www.oracle.com/security-alerts/cpuoct2021.htmlpatch, third-party-advisory
- https://pypi.org/project/urllib3/1.26.4/third-party-advisory
- https://github.com/urllib3/urllib3/commit/8d65ea1ecf6e2cdc27d42124e587c1b83a3118b0patch, third-party-advisory
- https://github.com/urllib3/urllib3/security/advisories/GHSA-5phf-pp7p-vc2rmitigation, third-party-advisory
- https://security.gentoo.org/glsa/202305-02vendor-advisory
- https://security.netapp.com/advisory/ntap-20240621-0007/
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.