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CVE-2026-27448

pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback PUBLISHED

Description (CNA)

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.

Affected (CNA)

Vendor / productVersions
pyca / pyopensslaffected >= 0.14.0, < 26.0.0

CWE

CWE-636

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.