CVE-2026-19650 in GitLab
Summary
by MITRE • 08/17/2026
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.2 before 18.11.11, 19.0 before 19.0.8, 19.1 before 19.1.6, and 19.2 before 19.2.4 that under certain conditions could have allowed an unauthenticated user to execute mutations via GET requests due to improper request validation in GraphQL multiplex query handling.
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Analysis
by VulDB Data Team • 08/17/2026
GitLab has addressed a critical security vulnerability affecting multiple versions of its Community Edition and Enterprise Edition software, specifically impacting releases from 18.2 up to but not including 18.11.11, as well as versions 19.0 prior to 19.0.8, 19.1 prior to 19.1.6, and 19.2 prior to 19.2.4. This flaw stems from improper request validation within the GraphQL multiplex query handling mechanism, which serves as a core component for processing complex data operations in GitLab's API layer. The vulnerability allows an unauthenticated user to execute mutations via standard GET requests, bypassing the intended authentication and authorization controls that should restrict such actions to authenticated users with appropriate permissions. This represents a significant deviation from secure design principles where state-changing operations are typically restricted to POST or PUT methods to prevent unintended execution through simple link clicks or automated scraping tools.
The technical root cause lies in how GitLab's GraphQL server processes multiplexed queries, which allow clients to bundle multiple requests into a single HTTP call for efficiency. In the affected versions, the validation logic failed to adequately distinguish between query operations intended for data retrieval and mutation operations designed to modify system state when these were submitted via GET methods. By leveraging this oversight, an attacker can craft specific GraphQL mutations that are executed without requiring valid session tokens or API keys. This bypass of authentication mechanisms is particularly dangerous because it enables remote code execution scenarios if the mutated actions involve integration with external services, database modifications, or configuration changes that could be exploited to escalate privileges or disrupt service availability.
From a risk perspective, this vulnerability aligns closely with CWE-284 Improper Access Control and CWE-798 Use of Hard-coded Credentials in contexts where authentication is bypassed entirely. It also maps to MITRE ATT&CK technique T1059 Command and Scripting Interpreter if the mutations allow for arbitrary command execution through GitLab's runner or CI/CD pipelines, although more commonly it falls under T1136 False Profiling or T1078 Valid Accounts depending on whether any partial authentication is required. The operational impact includes potential unauthorized modification of project settings, deletion of repositories, alteration of user permissions, and exposure of sensitive data through side effects triggered by the mutations. Attackers can automate these requests using simple HTTP clients, making exploitation straightforward and scalable across large deployments without needing sophisticated tooling or prior access credentials.
Mitigation requires immediate upgrading to patched versions including GitLab 18.11.11 or later for the 18.x branch, 19.0.8 or later for version 19.0, 19.1.6 or later for version 19.1, and 19.2.4 or later for version 19.2. Organizations should verify their current GitLab instance versions against these thresholds before applying updates to avoid service disruption during maintenance windows. Additionally, implementing Web Application Firewall rules that restrict GraphQL mutation endpoints to POST methods only can provide a temporary compensating control while upgrades are being planned. Security teams should also audit access logs for unusual patterns of GET requests targeting GraphQL endpoints containing mutation keywords such as createProject or deleteUser to identify potential exploitation attempts in the wild. Regular penetration testing focusing on API authentication bypasses and input validation gaps is recommended to ensure similar flaws do not persist in future releases, reinforcing defense-in-depth strategies around critical infrastructure components like version control platforms.