ruby2.7, ruby3.0, ruby3.2, ruby3.3 vulnerabilities

It was discovered that Ruby's Net::IMAP library did not properly verify
that TLS encryption was started after issuing a STARTTLS command. A remote
attacker could use this to perform a machine-in-the-middle attack and silently
bypass TLS encryption. (CVE-2026-42246)

It was discovered that Ruby's Net::IMAP library did not validate
string arguments passed to certain commands. A remote attacker could use
this to inject arbitrary IMAP commands. (CVE-2026-42257)

It was discovered that Ruby's Net::IMAP library was vulnerable to a
denial of service attack when authenticating with SCRAM-SHA1 or
SCRAM-SHA256. A hostile server could send a very large iteration count
value to cause excessive computation in the client. This issue only
affected ruby3.3. (CVE-2026-42256)