A critical remote code execution (RCE) vulnerability in GitHub could potentially allow attackers to execute arbitrary code on GitHub.com and GitHub Enterprise Server.

Uncovered by Wiz researchers, the now-patched bug exploited how GitHub handles server-side “git push” operations. By crafting malicious input within a standard Git push, an authenticated user could execute arbitrary commands via GitHub’s backend Git processing pipeline.

GitHub acknowledged the severity of the finding, with CISO Alexis Wales noting, “A finding of this caliber and severity is rare, earning one of the highest rewards available in our Bug Bounty program.”

GitHub fixed the issue on GitHub.com and released patches for all supported versions of GitHub Enterprise Server within hours of the report. However, Wiz said that 88% of Enterprise Server instances remained vulnerable on the internet at the time of public disclosure.

GitHub’s faulty processing of git push

The flaw, tracked as CVE-2026-3854, stemmed from how GitHub processes git push requests within its backend Git infrastructure. According to Wiz, the issue involves an internal component referred to as X-STAT, which sits in the path of GitHub’s server-side handling of Git operations.

Wiz researchers found that a specially crafted git push could pass maliciously structured input into X-STAT, where it was not safely handled before being incorporated into backend command execution. Because this processing happens server-side as part of GitHub’s normal handling of repository events, the input could influence how commands were constructed or executed within that pipeline.

The flaw received a near-critical CVSS rating of 8.8 out of 10, and was fixed in GitHub Enterprise Server versions 3.14.25 through 3.20.0. The flaw was categorized by GitHub as a “command injection” issue, resulting from “improper neutralization of special elements used in a command.”

AI was reportedly used in finding this flaw, using the IDA MCP (AI-augmented) reverse engineering tooling. “This is one of the first critical vulnerabilities discovered in closed-source binaries using AI, highlighting a shift in how these flaws are identified,” Wiz researcher Sagi Tzadik said in a blog post. “Despite the complexity of the underlying system, the vulnerability is remarkably easy to exploit.”

Full compromise across tenants

In its analysis, Wiz detailed how the issue could be escalated from initial command execution to full remote code execution on affected systems.

“On GitHub.com, this vulnerability allowed remote code execution on shared storage nodes. We confirmed that millions of public and private repositories belonging to other users and organizations were accessible on the affected nodes,” Tzadik said, adding that the impact was even more severe for self-hosted environments. On GitHub Enterprise Server, the vulnerability granted full server compromise, including access to all hosted repositories and internal secrets.

The article originally appeared in CSO.