CVE-2026-27448

EUVD-2026-12675
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.
Failing Open
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 12.34%
Affected Products (NVD)
VendorProductVersion
pyopensslpyopenssl
0.14 ≤
𝑥
< 26.0.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
pyopenssl
bookworm
no-dsa
bullseye
postponed
forky
26.1.0-1
fixed
sid
26.1.0-1
fixed
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
pyopenssl
bionic
needs-triage
focal
needs-triage
jammy
Fixed 21.0.0-1ubuntu0.1
released
noble
Fixed 23.2.0-1ubuntu0.1
released
questing
Fixed 25.0.0-1ubuntu0.1
released
resolute
not-affected
trusty
needs-triage
xenial
needs-triage