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

🗓️ 17 Mar 2026 23:24:30Reported by GoogleType

osv

osv🔗 osv.dev

pyOpenSSL could accept a connection when the server name callback raised an unhandled exception before version twenty six.

Reporter	Title	Published	Views	Family All 91
IBM Security Bulletins	Security Bulletin: IBM Watson Speech Services Cartridge is vulnerable to a security bypass in pyOpenSSL [CVE-2026-27448, CVE-2026-27459]	21 May 202615:10	–	ibm
IBM Security Bulletins	Security Bulletin: pyOpenSSL TLS SNI Callback Exception Handling Flaw Allows Security Bypass	4 May 202612:18	–	ibm
IBM Security Bulletins	Security Bulletin: Multiple Vulnerabilities in pyOpenSSL bundled with IBM Fusion, IBM Fusion HCI, and IBM Fusion Data Cataloging	18 May 202622:19	–	ibm
IBM Security Bulletins	Security Bulletin: IBM SOAR QRadar Plugin App is vulnerable to using components with known vulnerabilities	6 May 202616:21	–	ibm
ATTACKERKB	CVE-2026-27448	17 Mar 202623:24	–	attackerkb
AlpineLinux	CVE-2026-27448	17 Mar 202623:24	–	alpinelinux
CBLMariner	CVE-2026-27448 affecting package pyOpenSSL for versions less than 24.2.1-2	25 Mar 202622:53	–	cbl_mariner
Chainguard	CVE-2026-27448 vulnerabilities	18 Mar 202601:17	–	cgr
CNNVD	pyOpenSSL 安全漏洞	17 Mar 202600:00	–	cnnvd
CVE	CVE-2026-27448	17 Mar 202623:24	–	cve

Source	Link
github	www.github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst
github	www.github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27448.json
github	www.github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
nvd	www.nvd.nist.gov/vuln/detail/CVE-2026-27448
github	www.github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0

06 Jun 2026 18:29Current

5.9Medium risk

Vulners AI Score5.9

CVSS 46.3

EPSS0.00043

pyOpenSSL server name callback unhandled exception connection bypass version twenty six