This gem depends on the pttparty gem and has its version pinned to '0.21.0' in ruby-pardot.gemspec. Unfortunately, all versions '<= 0.23.2' are affected by an SSRF Vulnerability.
For details see: GHSA-hm5p-x4rq-38w4
Please update this dependency to the patched version '0.24.0' at the very least. I suggest using '~> 0.24.0' or even '~> 0.24' instead to unblock users from updating such security patches on dependencies in the future.