The darwinssl_connect_step1 function in lib/vtls/curl_darwinssl.c in libcurl 7.31.0 through 7.39.0, when using the DarwinSSL (aka SecureTransport) back-end for TLS, does not check if a cached TLS session validated the certificate when reusing the session, which allows man-in-the-middle attackers to spoof servers via a crafted certificate.<a href=http://cwe.mitre.org/data/definitions/295.html>CWE-295: Improper Certificate Validation</a> http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8151