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Hackers Earn Big Bounties for GitHub Enterprise Flaws

White hat hackers have earned tens of thousands of dollars in bounties after finding serious vulnerabilities in GitHub Enterprise.

GitHub Enterprise is the on-premises version of, for which organizations pay an annual fee of $2,500 for every 10 users. The product promises enterprise-grade security, 24/7 technical support, hosting options, and several administration features not available for

GitHub Enterprise versions 2.8.5, 2.8.6 and 2.8.7, released in January, patch several flaws rated critical and high severity, including ones that can be exploited to bypass authentication and remotely execute arbitrary code.

The researchers who discovered the vulnerabilities have started making their findings public, and information from GitHub and the experts themselves shows that they earned significant rewards.

GitHub included the Enterprise product in its bug bounty program at the beginning of the year, when it announced that the most severe bugs reported in January and February would also receive bonus rewards.

Two of the vulnerabilities rated critical were identified by Greece-based researcher Ioannis Kakavas. The expert discovered a couple of flaws in the Security Assertion Markup Language (SAML) implementation of GitHub Enterprise, and received a research grant to conduct a full assessment of SAML in GitHub.

Kakavas, who is currently the second best hacker in GitHub’s bug bounty program, earned a total of $27,000 for the flaws he uncovered. He recently published a blog post containing technical details and proof-of-concept (PoC) code.

Another critical flaw was discovered by German bug bounty hunter Markus Fenske. The expert found a weakness in the management console that could have been exploited to execute arbitrary commands on the GitHub Enterprise appliance.

Fenske has received a total of $18,000 for his findings, which includes a $10,000 bounty, the maximum reward offered by GitHub, and an $8,000 bonus.

Researcher Orange Tsai, who last year managed to hack a Facebook server, received $5,000 and a $5,000 bonus for responsibly disclosing a high severity SQL injection vulnerability related to the pre-receive hook APIs used by GitHub Enterprise.

GitHub said there was no evidence that the vulnerabilities identified by Fenske and Kakavas had been exploited in the wild.

Related: "Truffle Hog" Tool Detects Secret Key Leaks on GitHub

Related: GitHub Paid $100,000 Since Launch of Bug Bounty Program

Related: Attackers Used Leaked Passwords to Hack GitHub Accounts

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.