Siemens RUGGEDCOM ROS before 4.2.1 allows remote attackers to obtain sensitive information by sniffing the network for VLAN data within the padding section of an Ethernet frame.
https://ics-cert.us-cert.gov/advisories/ICSA-15-300-01
http://www.siemens.com/cert/pool/cert/siemens_security_advisory_ssa-921524.pdf