Improper Neutralization of Special Elements used in a Command ('Command Injection')
Jenkins Convert To Pipeline Plugin 1.0 and earlier uses basic string concatenation to convert Freestyle projects' Build Environment, Build Steps, and Post-build Actions to the equivalent Pipeline step invocations, allowing attackers able to configure Freestyle projects to prepare a crafted configuration that injects Pipeline script code into the (unsandboxed) Pipeline resulting from a convertion by Jenkins Convert To Pipeline Plugin.
CWE-77 - Command Injection
A command injection attack involves injecting an operating system command through the data input, which gets executed on the host operating system with the privileges of the victimized application. The impact of a command injection attack may range from loss of data confidentiality and integrity to unauthorized remote access to the hosting system. The attack may cause serious data breaches and system takeover.