The Mozilla Foundation has awarded five "bug bounties" worth $2,500 (£1,400) to a German security researcher who discovered vulnerabilities in its open source Firefox web browser.
Michael Krax received the cash for discovering security threats relating to chrome privileges on the browser, which could have led to users inadvertently downloading malicious code.
Mozilla started offering bug bounties last year and is financed by Linux desktop software company Linspire and millionaire internet investor Mark Shuttleworth.
Microsoft, by contrast, doesn’t award cash prizes to discoverers of vulnerabilities in its Internet Explorer browser.
Firefox users have been forced to upgrade their browsers against two major security threats in the last two months.
Mozilla says Firefox has been downloaded 30 million times since last year’s launch.