GitHub fixes RCE flaw that gave access to millions of private repos

In early March, GitHub patched a critical remote code execution vulnerability (CVE-2026-3854) that could have allowed attackers to access millions of private repositories. The flaw was reported on March 4, 2026, by researchers at cybersecurity firm Wiz through GitHub's bug bounty program. GitHub Chief Information Security Officer Alexis Wales said the company's security team reproduced and confirmed the vulnerability within 40 minutes and deployed a fix to GitHub.com less than two hours after receiving the report. CVE-2026-3854 affects GitHub.com, GitHub Enterprise Cloud, GitHub Enterprise Cloud with Data Residency, GitHub Enterprise Cloud with Enterprise Managed Users, and GitHub Enterprise Server. Successful exploitation requires only a single maliciously crafted 'git push' command and can grant full read/write access to private repositories on GitHub.com or vulnerable GitHub Enterprise servers to attackers with push access. The vulnerability lies in how GitHub handles user-supplied options during git push operations, with values passed by users being incorporated into internal server metadata without sufficient sanitization, allowing attackers to inject additional fields trusted by the downstream service. As Wales explained on Tuesday, an attacker could bypass sandboxing protections and execute arbitrary code on the server handling the push by chaining multiple injected values together. ​"Exploitation could expose the codebases of nearly all of the world's biggest enterpr...