ACE vulnerability in JaninoEventEvaluator  by QOS.CH logback-core
      upto and including version 1.5.12 in Java applications allows
      attacker to execute arbitrary code by compromising an existing
      logback configuration file or by injecting an environment variable
      before program execution.





Malicious logback configuration files can allow the attacker to execute 
arbitrary code using the JaninoEventEvaluator extension.



A successful attack requires the user to have write access to a 
configuration file. Alternatively, the attacker could inject a malicious 
environment variable pointing to a malicious configuration file. In both 
cases, the attack requires existing privilege.