GHSA-vp96-hxj8-p424
pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback
At a glance
- Published
- Updated
- CVE
- CVE-2026-27448
- Aliases
- PYSEC-2026-2268
- CVSS_V4
- CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U
Description
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.
Affected packages
| Package | Versions |
|---|---|
| PyPI · pyopenssl | introduced 0.14.0, fixed 26.0.0 |
References
- https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424 WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-27448 ADVISORY
- https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0 WEB
- https://github.com/pyca/pyopenssl PACKAGE
- https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27 WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |