CVE-2023-6955: GitLab Authorization Bypass Vulnerability

CVE-2023-6955 Overview

CVE-2023-6955 is a missing authorization check vulnerability (CWE-862) in GitLab Remote Development that affects multiple versions of GitLab Community and Enterprise editions. This security flaw allows an attacker to create a workspace in one group that is associated with an agent from another group, effectively bypassing intended group isolation boundaries.

The vulnerability exists due to insufficient authorization validation when handling workspace creation requests in the Remote Development feature. An unauthenticated attacker can exploit this flaw over the network without any user interaction, potentially compromising the integrity of group-based access controls within GitLab environments.

Critical Impact

Attackers can bypass group isolation controls, creating workspaces that leverage agents from unauthorized groups, potentially gaining access to resources and environments they should not have access to.

Affected Products

• GitLab Community Edition versions prior to 16.5.6
• GitLab Enterprise Edition versions prior to 16.5.6
• GitLab Community and Enterprise Edition versions 16.6 prior to 16.6.4
• GitLab Community and Enterprise Edition versions 16.7 prior to 16.7.2

Discovery Timeline

• 2024-01-12 - CVE-2023-6955 published to NVD
• 2025-05-05 - Last updated in NVD database

Technical Details for CVE-2023-6955

Vulnerability Analysis

This vulnerability is classified as a Missing Authorization (CWE-862) flaw in the GitLab Remote Development feature. The core issue stems from the application failing to perform proper authorization checks when a user attempts to create a workspace and associate it with a Kubernetes agent.

In GitLab's Remote Development architecture, workspaces are intended to be isolated within their respective groups, and agents should only be accessible to workspaces within the same group hierarchy. The vulnerability allows this isolation to be circumvented, enabling cross-group workspace-agent associations that violate the intended security model.

The attack can be performed remotely over the network and does not require any privileges or user interaction. While the confidentiality and availability impacts are limited, the integrity impact allows unauthorized modification of workspace configurations.

Root Cause

The root cause of CVE-2023-6955 is the absence of proper authorization validation in the GitLab Remote Development module when processing workspace creation requests. The application fails to verify whether the requesting user has appropriate permissions to access the target agent's group before allowing the workspace-agent association to be established.

This missing check allows users to reference agents from groups outside their authorized scope, bypassing the group-based isolation that should restrict which agents can be used for workspace provisioning.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no authentication, no user interaction, and low complexity to exploit. An attacker can craft malicious requests to the GitLab Remote Development API that specify an agent identifier belonging to a different group than the workspace being created.

The exploitation flow involves:

1. Identifying available agents across different GitLab groups
2. Crafting a workspace creation request that references an agent from an unauthorized group
3. Submitting the request to create a workspace with the cross-group agent association
4. Gaining access to the agent's resources and execution environment from the unauthorized workspace

Since no code examples are available from verified sources, administrators should consult the GitLab Issue Discussion for detailed technical information about the vulnerability mechanics.

Detection Methods for CVE-2023-6955

Indicators of Compromise

• Workspaces created with agent associations that span different group hierarchies
• Unexpected workspace creation activity from users who should not have access to specific agents
• Audit log entries showing workspace-agent bindings that violate group boundaries
• Anomalous API requests to the Remote Development endpoints with cross-group agent references

Detection Strategies

• Review GitLab audit logs for workspace creation events and verify the group membership of both the workspace and associated agent
• Implement monitoring rules to alert on workspace creation requests that reference agents outside the user's authorized groups
• Deploy SentinelOne Singularity Platform to detect anomalous API activity patterns targeting GitLab Remote Development endpoints
• Perform periodic audits of existing workspaces to identify any unauthorized cross-group agent associations

Monitoring Recommendations

• Enable comprehensive audit logging for all Remote Development operations in GitLab
• Configure alerts for workspace creation events and correlate them with agent group membership
• Monitor network traffic for unusual patterns in GitLab API requests, particularly those targeting /api/v4/workspaces endpoints
• Implement SentinelOne Cloud Workload Protection to monitor GitLab infrastructure for signs of exploitation

How to Mitigate CVE-2023-6955

Immediate Actions Required

• Upgrade GitLab to version 16.5.6 or later for the 16.5.x branch
• Upgrade GitLab to version 16.6.4 or later for the 16.6.x branch
• Upgrade GitLab to version 16.7.2 or later for the 16.7.x branch
• Audit existing workspaces to identify and remediate any unauthorized cross-group agent associations
• Review and restrict access to the Remote Development feature until patching is complete

Patch Information

GitLab has released security patches addressing this vulnerability in versions 16.5.6, 16.6.4, and 16.7.2. Organizations should upgrade to these versions or later to remediate the missing authorization check. The patches introduce proper authorization validation that verifies the user's group membership before allowing workspace-agent associations.

For detailed information about the fix and additional context, refer to the GitLab Issue Discussion.

Workarounds

• Temporarily disable the Remote Development feature if immediate patching is not feasible
• Implement network-level access controls to restrict which users can reach the Remote Development API endpoints
• Configure GitLab group visibility settings to minimize exposure of agent information across groups
• Use GitLab's IP allowlist feature to limit API access to trusted networks only

# Verify GitLab version and check for vulnerable installations
gitlab-rake gitlab:env:info | grep "GitLab information"

# Check current GitLab version
cat /opt/gitlab/embedded/service/gitlab-rails/VERSION

# Update GitLab to patched version (example for Omnibus installation)
sudo apt-get update && sudo apt-get install gitlab-ce=16.7.2-ce.0

# Reconfigure GitLab after update
sudo gitlab-ctl reconfigure