A server-side request forgery vulnerability exists in Jenkins URLTrigger Plugin 0.41 and earlier in URLTrigger.java that allows attackers with Overall/Read access to cause Jenkins to send a GET request to a specified URL. As of version 0.43, this form validation method no longer connects to a user provided URL.
github.com/jenkinsci/urltrigger-plugin
github.com/jenkinsci/urltrigger-plugin/commit/46220e69c220bacf8eb23911c8feba9dd68d1a26
github.com/jenkinsci/urltrigger-plugin/commit/aec43e370550b26636aa9cab0f23a5cbcffdc44f
jenkins.io/security/advisory/2018-06-25/#SECURITY-819
nvd.nist.gov/vuln/detail/CVE-2018-1000606