CVE-2026-92628: GitLab Race Condition Vulnerability

CVE-2026-92628 Overview

CVE-2026-92628 is a race condition vulnerability in GitLab Community Edition (CE) and Enterprise Edition (EE). The flaw affects the Model Context Protocol (MCP) search tool's shared state handling. Under specific timing conditions, search results could be returned under an incorrect user context, exposing data to unauthorized users.

The vulnerability is tracked as CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization. GitLab has released patches in versions 19.2.7, 19.3.3, and 19.4.1.

Critical Impact
Concurrent MCP search requests could leak search results across user boundaries, allowing one authenticated user to receive data intended for another.

Affected Products

GitLab CE/EE versions 18.6 through 19.2.6
GitLab CE/EE versions 19.3 through 19.3.2
GitLab CE/EE version 19.4.0

Discovery Timeline

2026-09-24 - CVE-2026-92628 published to the National Vulnerability Database (NVD)
2026-09-28 - Last updated in NVD database

Technical Details for CVE-2026-92628

Vulnerability Analysis

The vulnerability resides in the MCP search tool implementation within GitLab. The MCP server exposes GitLab search functionality to AI assistants and automated tooling through a standardized protocol. When concurrent requests execute against the shared state structure, the user context associated with a search response can desynchronize from the requesting user's identity.

An authenticated low-privileged attacker can issue requests timed to coincide with a victim's search operation. If the race wins, the attacker receives search results scoped to the victim's permissions. The result is unauthorized disclosure of repository content, issues, merge requests, or other searchable project data visible to the victim.

Exploitation requires network access to the GitLab instance and valid credentials. The attack complexity is high because the attacker must reliably win a narrow timing window between request processing stages in the MCP server.

Root Cause

The root cause is improper synchronization of shared state within the MCP search tool's request-handling path. The tool stores or references user context in a location that is not isolated per request. Under concurrent load, one request's response can be constructed using another request's authorization context, violating tenant isolation guarantees.

Attack Vector

The attack vector is network-based and requires authentication. An attacker with a valid GitLab account triggers MCP search queries in parallel with victim activity. Successful exploitation yields confidentiality impact only; integrity and availability are not affected. Because exploitation depends on winning a race condition against an active victim session, reliable exploitation is non-trivial.

No public proof-of-concept or exploit code is available. Full technical details are documented in GitLab Work Item #621933.

Detection Methods for CVE-2026-92628

Indicators of Compromise

Unexpected search results appearing in MCP client logs that reference projects or resources the authenticated user does not normally access
Repeated, rapid MCP search tool invocations from a single session that align in time with other users' search activity
Anomalous spikes in concurrent MCP search requests against the GitLab API endpoint

Detection Strategies

Audit the GitLab application logs for /api/v4/mcp and MCP search tool endpoints, correlating requesting user IDs with the projects referenced in response payloads
Baseline normal MCP tool usage per user and alert on sudden deviations in search frequency or project scope
Review GitLab audit events for cross-project access patterns inconsistent with user role assignments

Monitoring Recommendations

Enable verbose MCP server request logging and forward events to a centralized SIEM for correlation
Monitor authentication and session telemetry alongside MCP tool access to identify unusual concurrency patterns
Track GitLab release channels for additional advisories referencing MCP components

How to Mitigate CVE-2026-92628

Immediate Actions Required

Upgrade GitLab CE/EE to version 19.4.1, 19.3.3, or 19.2.7 depending on the deployed branch
Inventory all self-managed GitLab instances and confirm the MCP feature exposure before and after patching
Restrict MCP tool access to trusted integrations until patching is complete

Patch Information

GitLab addressed the race condition in the GitLab 19.4.1 Patch Release. Fixes are also included in the 19.3.3 and 19.2.7 patch releases. Administrators running self-managed GitLab should apply the patch for their respective minor version branch.

Workarounds

Disable the MCP search tool integration if not required by workflow
Limit MCP endpoint access via network controls or reverse proxy rules to known client IP ranges
Reduce MCP server concurrency where configurable to shrink the exploitable timing window until patches are applied

bash

# Example: upgrade self-managed GitLab on Debian/Ubuntu to a patched release
sudo apt-get update
sudo apt-get install gitlab-ee=19.4.1-ee.0
sudo gitlab-ctl reconfigure
sudo gitlab-ctl restart