Not Failing Securely ('Failing Open') Affecting pyopenssl package, versions [0.14,26.0.0)
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-PYOPENSSL-15674458
- published17 Mar 2026
- disclosed16 Mar 2026
- creditLeury Castillo
Introduced: 16 Mar 2026
NewCVE-2026-27448 (opens in a new tab)How to fix?
Upgrade pyopenssl to version 26.0.0 or higher.
Overview
Affected versions of this package are vulnerable to Not Failing Securely ('Failing Open') via the set_tlsext_servername_callback function. An attacker can bypass security-sensitive checks by causing an unhandled exception in the callback, which results in the connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it.