Siemens SIMATIC S7-300 Profinet-enabled CPU devices with firmware before 3.2.12 and SIMATIC S7-300 Profinet-disabled CPU devices with firmware before 3.3.12 allow remote attackers to cause a denial of service (defect-mode transition) via crafted (1) ISO-TSAP or (2) Profibus packets.
https://ics-cert.us-cert.gov/advisories/ICSA-16-161-01
https://cert-portal.siemens.com/productcert/pdf/ssa-818183.pdf
http://www.siemens.com/cert/pool/cert/siemens_security_advisory_ssa-818183.pdf