CVE-2026-27448Low▾ SunlitpyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback
▾ Sunlit zone — Low / medium · no exploitation signal
impact 13.8 · likelihood 0 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Exploit-prediction probability, daily snapshots since Jul 13.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
0.2%
Last analysed / modified upstream
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.
Unhandled exceptions now result in rejecting the connection.
Credit to Leury Castillo for reporting this issue.
pyopenssl >= 0.14.0, < 26.0.0Upgrade to a patched release:
pyopenssl 26.0.0Connected by shared product, vendor, weakness, or advisory.