The libcurl API function called `curl_maprintf()` before version 7.51.0 can be tricked into doing a double-free due to an unsafe `size_t` multiplication, on systems using 32 bit `size_t` variables.
https://www.tenable.com/security/tns-2016-21
https://security.gentoo.org/glsa/201701-47
https://curl.haxx.se/docs/adv_20161102D.html
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2016-8618
https://access.redhat.com/errata/RHSA-2018:3558
https://access.redhat.com/errata/RHSA-2018:2486
http://www.securitytracker.com/id/1037192
http://www.securityfocus.com/bid/94098
http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html