Dawid Czagan
Dawid Czagan, leader of security experts at Silesia Security Lab, has found security vulnerabilities in Google, Yahoo, Mozilla, Microsoft, Twitter, BlackBerry and other companies. Due to the severity of many bugs, he received numerous awards for his findings.

His security work is acknowledged by the following companies/projects (he is listed by his name or nickname: dawidczagan):

(*) Mozilla will publish their Hall of Fame soon
(**) Microsoft is working on a fix and will publish their Security Bulletin soon

Moreover, Dawid has found security vulnerabilities in further bug bounty programs, which don’t publicly acknowledge bug hunters on their sites (Asana, bitcoin.de, bitcurex.com).