Ubuntu 18.04 Ruby Security Advisory USN-8431-1 Remote Access Issues

A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 18.04 LTS - Ubuntu 16.04 LTS Summary: Ruby could allow unintended access to network services. Software Description: - ruby2.5: Object-oriented scripting language - ruby2.3: Object-oriented scripting language Details: It was discovered that Ruby's Net::IMAP library did not properly verify that Transport Layer Security (TLS) encryption was started after issuing a STARTTLS command. A remote attacker could possibly use this issue to perform a machine-in-the-middle attack and silently bypass TLS encryption. (CVE-2026-42246) It was also discovered that Ruby's Net::IMAP library did not validate string arguments passed to certain commands. A remote attacker could possibly use this issue to inject arbitrary IMAP commands. (CVE-2026-42257)