Improper Certificate Validation Affecting urllib3 package, versions [1.26.0,2.8.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-URLLIB3-20302844
- published30 Sept 2026
- disclosed29 Sept 2026
- creditYu-Fu Fu, Seth Larson, Yonatan Magier
Introduced: 29 Sep 2026
NewCVE-2026-97687 (opens in a new tab)How to fix?
Upgrade urllib3 to version 2.8.0 or higher.
Overview
urllib3 is a HTTP library with thread-safe connection pooling, file post, and more.
Affected versions of this package are vulnerable to Improper Certificate Validation in the connect method of src/urllib3/connection.py when an HTTPS proxy is configured with proxy_ssl_context while the target server uses a different certificate-verification policy. Due to the proxy's TLS settings not being isolated from the target's TLS settings, the proxy's ssl_context is incorrectly applied to the target connection (or vice versa), allowing an attacker to bypass certificate validation for either the proxy or the target server and perform a MitM attack.
Note: This is only exploitable when an HTTPS proxy is configured with proxy_ssl_context and the target server uses a different certificate-verification policy.