Path traversal in GitHub Enterprise Server leading to arbitrary file reading when building a GitHub Pages site

Summary

A path traversal vulnerability was identified in GitHub Enterprise Server that allowed arbitrary file reading when building a GitHub Pages site. To exploit this vulnerability, an attacker would need permission to create and build a GitHub Pages site on the GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server since 3.7 and was fixed in version 3.7.19, 3.8.12, 3.9.7, 3.10.4, and 3.11.1. This vulnerability was reported via the GitHub Bug Bounty program.