CVE-2021-20230

A flaw was found in stunnel, where it improperly validates client certificates when it is configured to use both redirect and verifyChain options. This flaw allows an attacker with a certificate signed by a Certificate Authority, which is not the one accepted by the stunnel server, to access the tunneled service instead of being redirected to the address specified in the redirect option. The highest threat from this vulnerability is to confidentiality.

This issue did not affect the versions of stunnel as shipped with Red Hat Enterprise Linux 5, 6, and 7 as they did not include support for the "redirect" option.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.