Name: CVE-2026-27448: Not Failing Securely
Creator: Rapid7
Published: 2026-03-18T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-27448, CVSS 5.3, EPSS 0.00407

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.

CVSS Details

CVSS 4.0 Base Score: 1.7 (LOW)
CVSS 4.0 Vector: (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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)
CVSS 3.1 Base Score: 5.3
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Alpine Linux	—	Upgrade py3-openssl	Apr 27, 2026	Mar 17, 2026
Debian	—	Upgrade pyopenssl	Jul 23, 2026	Jul 23, 2026
Redhat_linux	—	No solution exists	Jul 17, 2026	Mar 17, 2026
Ubuntu	—	Upgrade python3-openssl (Ubuntu Pro)Upgrade python-openssl (Ubuntu Pro)Upgrade python3-openssl	Mar 24, 2026	Mar 23, 2026

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CVSS Details

Covered by Rapid7

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