Jenkins versions 2.56 and earlier as well as 2.46.1 LTS and earlier are vulnerable to an XStream: Java crash when trying to instantiate void/Void.

Jenkins versions 2.56 and earlier as well as 2.46.1 LTS and earlier are vulnerable to a login command which allowed impersonating any Jenkins user. The `login` command available in the remoting-based CLI stored the encrypted user name of the successfully authenticated user in a cache file used to authenticate further commands. Users with sufficient permission to create secrets in Jenkins, and download their encrypted values (e.g. with Job/Configure permission), were able to impersonate any other Jenkins user on the same instance.

Jenkins versions 2.56 and earlier as well as 2.46.1 LTS and earlier are vulnerable to an unauthenticated remote code execution. An unauthenticated remote code execution vulnerability allowed attackers to transfer a serialized Java `SignedObject` object to the Jenkins CLI, that would be deserialized using a new `ObjectInputStream`, bypassing the existing blacklist-based protection mechanism. We're fixing this issue by adding `SignedObject` to the blacklist. We're also backporting the new HTTP CLI protocol from Jenkins 2.54 to LTS 2.46.2, and deprecating the remoting-based (i.e. Java serialization) CLI protocol, disabling it by default.

Jenkins through 2.93 allows remote authenticated administrators to conduct XSS attacks via a crafted tool name in a job configuration form, as demonstrated by the JDK tool in Jenkins core and the Ant tool in the Ant plugin, aka SECURITY-624.