cURL and applications linked against libcurl support “OCSP stapling”, also known as the TLS Certificate Status Request extension (using the CURLOPT_SSL_VERIFYSTATUS option). When telling cURL to use this feature, it uses that TLS extension to ask for a fresh proof of the server’s certificate’s validity. If the server doesn’t support the extension, or fails to provide said proof, cURL is expected to return an error. Due to a coding mistake, the code that checks for a test success or failure, ends up always thinking there’s valid proof, even when there is none or if the server doesn’t support the TLS extension in question.