GitLab RCE PoC Published for Authenticated Users on Unpatched Servers

Remote Code Execution Vulnerability Disclosed

Security researcher Yuhang Wu at depthfirst has released a working proof-of-concept (PoC) exploit for a remote code execution (RCE) vulnerability in unpatched self-managed GitLab 18.11.3 servers. The exploit allows an authenticated user to execute commands as the 'git' user by committing two specially crafted Jupyter notebooks and requesting their diff.

Affected Versions and Impact

The vulnerability impacts GitLab Community Edition (CE) and Enterprise Edition (EE) across several version ranges: 15.2.0 through 18.10.7, 18.11.0 through 18.11.4, and 19.0.0 through 19.0.1. The underlying issues stem from bugs in the Oj JSON parser, affecting published gems 3.13.0 through 3.17.1. Successful exploitation could expose sensitive data such as source code, Rails secrets, service credentials, and CI/CD data, depending on deployment isolation.

Required Actions for Self-Managed Instances

GitLab.com instances were patched by June 10, and dedicated customers do not need to take action. However, operators of self-managed GitLab instances must upgrade to a supported release containing the fix. The first fixed releases are 18.10.8, 18.11.5, and 19.0.2. There is no temporary workaround available; upgrading is the only recommended mitigation. Users of Helm and Operator deployments must verify the GitLab version within the Webservice image, not just the chart or Operator version.

Technical Details and CVE Status

The vulnerability chain involves GitLab's notebook renderer passing repository-controlled .ipynb JSON to Oj::Parser.usual.parse within a Puma worker. This process sends attacker-controlled data into Oj's native parser state. The depthfirst analysis indicates one bug controls a callback pointer, while another leaks a heap address. Neither depthfirst's disclosure nor GitLab's release notes have provided CVE identifiers or CVSS scores for these specific bugs.