Yahoo has paid out a total of more than $1.6 million since the launch of its public bug bounty program in 2013, the tech giant reported on Tuesday.

Yahoo teamed up with HackerOne in October 2013 and launched a proper bug bounty program after researchers complained that they only got low-value vouchers and Yahoo-themed swag for reporting serious vulnerabilities.

Bug bounty hunters can now earn up to $15,000 for critical flaws found in the company’s domains and properties, which include Yahoo and Flickr websites and apps, Brightroll, Flurry, Media Group One, Polyvore and Yahoo Small Business.

In July 2015, the company reported that it had paid out over $1 million since the launch of its program, and now the total amount has increased to more than $1.6 million.

According to HackerOne, Yahoo received more than 12,000 vulnerability reports from 2,200 hackers. The company said 19 percent of these reports, roughly 2,200, were eligible for a payment.

“Security is an investment, and Yahoo has invested in some of the best pen testers in the business. But like any investment portfolio, it’s smart to diversify,” said Bob Lord, Yahoo’s chief information security officer. “Today, one of the best investments a company can make is to crowd-source the best and brightest in the pen test community to find security issues before criminals do.”

HackerOne reported that Yahoo has one of the most successful bug bounty programs on its platform and it regularly ranks in the Top 10.

The list of researchers rewarded by Yahoo this year includes Jouko Pynnönen of Finland-based software company Klikki Oy, who received $10,000 after reporting a stored cross-site scripting (XSS) vulnerability in Yahoo Mail, and researcher Behrouz Sadeghipour, who earned $2,000 for demonstrating that the recently disclosed ImageTragick vulnerability could be exploited on the Polyvore website.

In comparison, as part of their bug bounty programs, Facebook has paid out over $4.3 million since 2011 and Google awarded hackers more than $6 million since 2010.

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