Commercial support for curl and libcurl is offered and provided by Daniel Stenberg (the curl founder) through the company wolfSSL.
wolfSSL offers world-wide commercial support on curl done by the masters of curl. wolfSSL handles curl customization, ports to new operating systems, feature development, patch maintenance, bug fixing, upstreaming, training, code reviews of libcurl API use, security scanning your curl use and more - with several different support options from basic up to full 24/7 support. With guaranteed response times.
See the support page for contact details.