Security Bulletin: pyOpenSSL TLS SNI Callback Exception Handling Flaw Allows Security Bypass

Summary 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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this...

CLSA-2026-1776098295 pyOpenSSL: Fix of CVE-2026-27448

CVE-2026-27448: fix fail-open in settlsextservernamecallback when callback raises exception...

MGASA-2026-0074 Updated python-openssl packages fix security vulnerabilities

pyOpenSSL allows TLS connection bypass via unhandled callback exception in settlsextservernamecallback. CVE-2026-27448 pyOpenSSL DTLS cookie callback buffer overflow. CVE-2026-27459...

OESA-2026-1731 pyOpenSSL security update

pyOpenSSL is a rather thin wrapper around a subset of the OpenSSL library. With thin wrapper we mean that a lot of the object methods do nothing more than calling a corresponding function in the OpenSSL library. Security Fixes: A security vulnerability exists in the PyOpenSSL library's...

OESA-2026-1734 pyOpenSSL security update

pyOpenSSL is a rather thin wrapper around a subset of the OpenSSL library. With thin wrapper we mean that a lot of the object methods do nothing more than calling a corresponding function in the OpenSSL library. Security Fixes: A security vulnerability exists in the PyOpenSSL library's...

OESA-2026-1730 pyOpenSSL security update

pyOpenSSL is a rather thin wrapper around a subset of the OpenSSL library. With thin wrapper we mean that a lot of the object methods do nothing more than calling a corresponding function in the OpenSSL library. Security Fixes: A security vulnerability exists in the PyOpenSSL library's...

Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : pyOpenSSL vulnerabilities (USN-8115-1)

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-8115-1 advisory. It was discovered that pyOpenSSL incorrectly handled exceptions in the tlsextservername callback. This could result in connections...

SUSE CVE-2026-27448

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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for...

CVE-2026-27448

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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for...

AZL-80031 CVE-2026-27448 affecting package pyOpenSSL for versions less than 24.2.1-2

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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for...

UBUNTU-CVE-2026-27448

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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for...

CVE-2026-27448

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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for...

CVE-2026-27448 pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback

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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for...

CVE-2026-27448

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 settlsextservernamecallback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for...

CVE-2026-27448

CVE-2026-27448 is a pyOpenSSL vulnerability (SNI/TLSEXT callback) where an unhandled exception in set_tlsext_servername_callback could cause a connection to be accepted. IBM security notes reiterate that this flaw exists in pyOpenSSL versions prior to 26.0.0 and that starting with 26.0.0 unhandle...

pyOpenSSL 安全漏洞

pyOpenSSL is an open-source Python library that encapsulates OpenSSL from the Python Cryptographic Authority project. Versions of pyOpenSSL from 0.14.0 to 26.0.0 contained security vulnerabilities. These vulnerabilities stemmed from unhandled exceptions in the settlsextservername Callback functio...

Not Failing Securely ('Failing Open')

Overview Affected versions of this package are vulnerable to Not Failing Securely 'Failing Open' via the settlsextservernamecallback function. An attacker can bypass security-sensitive checks by causing an unhandled exception in the callback, which results in the connection being accepted. If a...

GHSA-VP96-HXJ8-P424 pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback

If a user provided callback to settlsextservernamecallback 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...

pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback

If a user provided callback to settlsextservernamecallback 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...

PT-2026-25778

Name of the Vulnerable Software and Affected Versions pyOpenSSL versions 0.14.0 through 25.9.9 Description pyOpenSSL is a Python wrapper around the OpenSSL library. If a user-provided callback to the set tlsext servername callback function raised an unhandled exception, a connection would be...