The following flaw was found in Jenkins:

A vulnerability in the Jenkins remoting module allowed unauthenticated remote attackers to open a JRMP listener on the server hosting the Jenkins master process, which allowed arbitrary code execution.

External References:

https://wiki.jenkins-ci.org/display/SECURITY/Jenkins+Security+Advisory+2016-02-24

Multiple unspecified API endpoints in Jenkins before 1.650 and LTS before 1.642.2 allow remote authenticated users to execute arbitrary code via serialized data in an XML file, related to XStream and groovy.util.Expando.

The following flaw was found in Jenkins:

Unsafe deserialization allows unauthenticated remote attackers to run arbitrary code on the Jenkins master.

This flaw could allow unauthenticated remote attackers to run arbitrary code on Jenkins.

Mitigation:

https://jenkins-ci.org/content/mitigating-unauthenticated-remote-code-execution-0-day-jenkins-cli

External References:

https://wiki.jenkins-ci.org/display/SECURITY/Jenkins+Security+Advisory+2015-11-11

Jenkins before 1.650 and LTS before 1.642.2 do not use a constant-time algorithm to verify CSRF tokens, which makes it easier for remote attackers to bypass a CSRF protection mechanism via a brute-force approach.