The web server on Siemens SCALANCE X-300 switches with firmware before 4.0 and SCALANCE X 408 switches with firmware before 4.0 allows remote attackers to cause a denial of service (reboot) via malformed HTTP requests.
https://cert-portal.siemens.com/productcert/pdf/ssa-321046.pdf
http://www.siemens.com/innovation/pool/de/forschungsfelder/siemens_security_advisory_ssa-321046.pdf