Improper Certificate Validation in Stunnel - CVE-2021-20230

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Main Vulnerability Database Vulnerabilities #VU50843

Improper Certificate Validation in Stunnel - CVE-2021-20230

Published: February 22, 2021


Vulnerability identifier: #VU50843
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-20230
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to improper client certificate validation, when redirect and verifyChain options are used. A remote attacker can bypass implemented security restrictions with a any valid certificated and gain access to sensitive information.


Affected software

Stunnel
Gentoo Linux
SUSE CaaS Platform
SUSE Manager Proxy
SUSE Manager Retail Branch Server
SUSE Manager Server
SUSE Enterprise Storage
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux Server - TUS
SUSE Linux Enterprise Server for SAP
SUSE Linux Enterprise High Performance Computing
SUSE Linux Enterprise Server
SUSE Linux Enterprise Module for Server Applications
Ubuntu
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
Red Hat Enterprise Linux Server for x86_64 - Update Services for SAP Solutions
stunnel4 (Ubuntu package)
stunnel
stunnel-debuginfo
stunnel-debugsource
stunnel (Red Hat package)
Red Hat Advanced Cluster Management for Kubernetes

How to mitigate CVE-2021-20230

Install updates from vendor's website.

Stunnel - update to 5.57
stunnel4 (Ubuntu package) - addressed in versions Ubuntu Pro, 3:5.56-1ubuntu0.2
Red Hat Advanced Cluster Management for Kubernetes - addressed in versions 2.0.8, 2.1.5
stunnel - addressed in versions 5.44-3.8.1, 5.57-3.11.1
stunnel-debuginfo - addressed in versions 5.44-3.8.1, 5.57-3.11.1
stunnel-debugsource - addressed in versions 5.44-3.8.1, 5.57-3.11.1
stunnel (Red Hat package) - addressed in versions 5.48-6.el8_1, 5.48-6.el8_2, 5.56-5.el8_3

External References

Related Security Bulletins