Stored XSS vulnerability in GitHub Enterprise Server leading to injection of arbitrary attributes

A stored XSS vulnerability was identified in GitHub Enterprise Server that allowed the injection of arbitrary attributes. This injection was blocked by Github's Content Security Policy (CSP). This vulnerability affected all versions of GitHub Enterprise Server prior to 3.6 and was fixed in versions 3.3.11, 3.4.6 and 3.5.3. This vulnerability was reported via the GitHub Bug Bounty program.