CVE-2026-4873: do not reuse a clear-text STARTTLS connection when the new
transfer requires TLS, so an IMAP, SMTP or POP3 request that mandates TLS is
not sent over an unencrypted connection
CVE-2026-6253: restore the proxy credentials set via options on every
redirect so credentials belonging to the first proxy are not disclosed to a
second, different proxy
CVE-2026-6429: drop credentials that were not set through CURLOPT_USERNAME
on redirect so a netrc password established for the first host is not sent to
the redirect target over a reused connection or proxy
CVE-2026-8924: trim trailing dots from the request and cookie domains before
the public suffix list check so a trailing-dot domain cannot set a super
cookie scoped to an unrelated site