CVE-2026-27448 — pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback
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`…
Published: 2026-03-17 · CVSS: 1.7 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7