Jenkins 2.73.1 and earlier, 2.83 and earlier bundled a version of the commons-httpclient library with the vulnerability CVE-2012-6153 that incorrectly verified SSL certificates, making it susceptible to man-in-the-middle attacks. This library is widely used as a transitive dependency in Jenkins plugins. The fix for CVE-2012-6153 was backported to the version of commons-httpclient that is bundled in core and made available to plugins.
A race condition during Jenkins 2.94 and earlier; 2.89.1 and earlier startup could result in the wrong order of execution of commands during initialization. There is a very short window of time after startup during which Jenkins may no longer show the 'Please wait while Jenkins is getting ready to work' message but Cross-Site Request Forgery (CSRF) protection may not yet be effective.
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.
The remoting module in Jenkins before 2.32 and LTS before 2.19.3 allows remote attackers to execute arbitrary code via a crafted serialized Java object, which triggers an LDAP query to a third-party server.