An issue was discovered in TCPDF before 6.8.0. If libcurl is used, CURLOPT_SSL_VERIFYHOST and CURLOPT_SSL_VERIFYPEER are set unsafely.
https://github.com/tecnickcom/TCPDF/compare/6.7.8...6.8.0
https://github.com/tecnickcom/TCPDF/commit/aab43ab0a824e956276141a28a24c7c0be20f554