CVE-2026-27448: pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback
pyca · pyopenssl
Affected: pyca pyopenssl · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 21% of scored CVEs
DescriptionCVE.org
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 products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- pyca · pyopenssl>= 0.14.0, < 26.0.0
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- pyca
- Published
- March 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-27448 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.