Oracle Linux: CVE-2021-32066: ELSA-2021-3020: ruby:2.7 security update (IMPORTANT) (Multiple Advisories)

An issue was discovered in Ruby through 2.6.7, 2.7.x through 2.7.3, and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response, which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command, aka a "StartTLS stripping attack."
Ruby's Net::IMAP module did not raise an exception when receiving an unexpected response to the STARTTLS command and the connection was not upgraded to use TLS. A man-in-the-middle attacker could use this flaw to prevent Ruby applications using Net::IMAP to enable TLS encryption for a connection to an IMAP server and subsequently eavesdrop on or modify data sent over the plain text connection.