A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153 and earlier, LTS 2.138.3 and earlier in stapler/core/src/main/java/org/kohsuke/stapler/MetaClass.java that allows attackers to invoke some methods on Java objects by accessing crafted URLs that were not intended to be invoked this way.
https://access.redhat.com/errata/RHBA-2019:0024
http://packetstormsecurity.com/files/166778/Jenkins-Remote-Code-Execution.html
https://github.com/flags-alt/abyss-c2
https://github.com/wyqsgy/vulnark
https://github.com/Yamewrong/cve-lab
https://github.com/smokeintheshell/CVE-2018-1000861
https://github.com/advisories/GHSA-hhpm-5cp2-hg4x
https://github.com/1NTheKut/CVE-2019-1003000_RCE-DETECTION
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-1000861
https://jenkins.io/security/advisory/2018-12-05/#SECURITY-595