guzzlehttp/guzzle: cURL handlers now reject unsupported HTTPS proxies
GuzzleHttp\Handler\CurlHandler and GuzzleHttp\Handler\CurlMultiHandler now detect whether the installed libcurl supports HTTPS proxies and reject requests configured with an https:// proxy if unsupported, throwing a GuzzleHttp\Exception\RequestException.
What changed
GuzzleHttp\Handler\CurlHandler and GuzzleHttp\Handler\CurlMultiHandler now detect whether the installed libcurl supports HTTPS proxies and reject requests configured with an https:// proxy if unsupported, throwing a GuzzleHttp\Exception\RequestException. Previously, libcurl older than 7.50.2 silently downgraded to plaintext.
Who it affects
Applications using Guzzle's built-in cURL handlers with an https:// proxy and libcurl older than 7.50.2, or any libcurl without HTTPS-proxy support.
What to do today
Upgrade to guzzlehttp/guzzle 7.12.1 or later. If unable to upgrade, verify libcurl HTTPS-proxy support before configuring an https:// proxy.