CVE-2026-2726 in Community Edition
Summary
by MITRE • 03/25/2026
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 11.10 before 18.8.7, 18.9 before 18.9.3, and 18.10 before 18.10.1 that could have allowed an authenticated user to perform unauthorized actions on merge requests in other projects due to improper access control during cross-repository operations.
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Analysis
by VulDB Data Team • 04/01/2026
This vulnerability represents a critical access control flaw in GitLab's merge request functionality that could enable authenticated users to manipulate merge requests in projects they do not have proper authorization to access. The issue specifically affects GitLab Community Edition and Enterprise Edition installations across multiple version ranges, creating a persistent security risk that spans from version 11.10 through 18.8.6, 18.9 through 18.9.2, and 18.10 through 18.10.0. The vulnerability stems from inadequate validation of user permissions during cross-repository operations, allowing privilege escalation through merge request manipulation. This type of flaw falls under CWE-284 which specifically addresses improper access control vulnerabilities, where the system fails to properly enforce access restrictions for operations that should be limited to authorized users only. The attack vector involves an authenticated user leveraging the system's insufficient permission checks to perform unauthorized actions on merge requests within other projects, potentially leading to unauthorized code changes or workflow disruptions.
The technical implementation of this vulnerability occurs during cross-repository merge request operations where the system fails to properly validate whether the authenticated user has sufficient permissions to access or modify merge requests in projects they do not own or have explicit access to. This flaw allows for unauthorized actions such as modifying merge request settings, adding or removing participants, changing merge request status, or performing other administrative functions that should be restricted to project members with appropriate access levels. The vulnerability's impact extends beyond simple information disclosure to potentially enable code injection or manipulation attacks if the user can escalate their privileges to include code review and merge capabilities. From an operational perspective, this represents a significant risk to software development workflows as it could allow malicious actors or compromised accounts to interfere with other teams' code review processes, potentially introducing backdoors or malicious code into production environments. The flaw essentially creates a pathway for unauthorized users to bypass project-level access controls and manipulate merge request workflows across different repositories.
Organizations using affected GitLab versions face substantial operational risks including potential code integrity compromises, unauthorized access to sensitive development workflows, and possible disruption of collaborative development processes. The vulnerability could enable attackers to manipulate merge request approvals, block legitimate code reviews, or even introduce malicious code changes that would not be properly vetted by authorized project members. This type of access control bypass is particularly concerning in enterprise environments where multiple teams collaborate on shared code repositories and where proper code review processes are critical for maintaining software quality and security. The remediation process requires immediate patching of affected systems, with organizations needing to carefully evaluate their current GitLab installations to identify which versions are vulnerable and implement the appropriate security updates. Security teams should also conduct thorough access control audits to ensure that no unauthorized modifications have occurred during the vulnerability window. From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and T1531 which addresses credential access through privilege escalation. The issue demonstrates how insufficient access control validation during cross-functional operations can create significant security gaps that traditional security measures might not detect or prevent. Organizations should implement additional monitoring for merge request activities and establish automated alerts for unusual merge request modifications that could indicate unauthorized access attempts.