Protocol downgrade required TLS bypassed

Open Source Vulnerabilities CVE-2021-22946

A user can tell curl >= 7.20.0 and <= 7.78.0 to require a successful upgrade to TLS when speaking to an IMAP, POP3 or FTP server (`--ssl-reqd` on the command line or`CURLOPT_USE_SSL` set to `CURLUSESSL_CONTROL` or `CURLUSESSL_ALL` withlibcurl). This requirement could be bypassed if the server would return a properly crafted but perfectly legitimate response.This flaw would then make curl silently continue its operations **withoutTLS** contrary to the instructions and expectations, exposing possibly sensitive data in clear text over the network.

Open Source Vulnerabilities CURL-CVE-2021-22946

A user can tell curl to **require** a successful upgrade to TLS when speaking to an IMAP, POP3 or FTP server (`--ssl-reqd` on the command line or `CURLOPT_USE_SSL` set to `CURLUSESSL_CONTROL` or `CURLUSESSL_ALL` with libcurl). This requirement could be bypassed if the server would return a properly crafted but perfectly legitimate response. This flaw would then make curl silently continue its operations **without TLS** contrary to the instructions and expectations, exposing possibly sensitive data in clear text over the network.