Versions Affected: all versions from 2.0-alpha1 to 2.8.1
When using the TCP socket server or UDP socket server to receive serialized log events from another application, a specially crafted binary payload can be sent that, when deserialized, can execute arbitrary code.
Java 7+ users should migrate to version 2.8.2 or avoid using the socket server classes. Java 6 users should avoid using the TCP or UDP socket server classes, or they can manually backport the security fix from 2.8.2: <https://git-wip-us.apache.org/repos/asf?p=logging-log4j2. git;h=5dcc192>
Credit: This issue was discovered by Marcio Almeida de Macedo of Red Team at Telstra