RCE vulnerability in Jenkins AWS SAM Plugin

AWS SAM Plugin 1.2.2 and earlier does not configure its YAML parser to prevent the instantiation of arbitrary types. This results in a remote code execution (RCE) vulnerability exploitable by users able to configure a job or control the contents of a previously configured "AWS SAM deploy application" build step’s YAML SAM template file (template.yaml or equivalent) file.

AWS SAM Plugin 1.2.3 configures its YAML parser to only instantiate safe types.