CVE-2026-6896 in GitLab
Summary
by MITRE • 07/09/2026
GitLab has remediated an issue in GitLab EE affecting all versions from 13.11 before 18.11.7, 19.0 before 19.0.4, and 19.1 before 19.1.2 that under certain conditions could have allowed an authenticated user with developer-role permissions to execute arbitrary scripts in another user's browser session due to improper sanitization of user-supplied input.
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Analysis
by VulDB Data Team • 07/09/2026
This vulnerability represents a critical cross-site scripting flaw that exploited insufficient input validation mechanisms within GitLab's enterprise edition platform. The issue affected multiple version streams including 13.11 through 18.11.6, 19.0 through 19.0.3, and 19.1 through 19.1.1, creating a widespread attack surface for malicious actors. The vulnerability stems from improper sanitization of user-supplied input that occurred during the processing of web requests, allowing attackers to inject malicious scripts into the application's response handling. Under specific conditions, an authenticated user possessing developer-level permissions could manipulate input fields or parameters to inject JavaScript code that would execute within another user's browser session. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting attacks and aligns with attack patterns documented in the MITRE ATT&CK framework under T1059.007 for Scripting and T1566.001 for Spearphishing Attachment, as attackers could leverage this flaw to deliver malicious payloads through compromised developer accounts.
The operational impact of this vulnerability extends beyond simple script execution, as it enables session hijacking and privilege escalation attacks that could compromise entire user bases within affected GitLab installations. When an authenticated developer with sufficient permissions injects malicious code into a vulnerable application component, the injected scripts execute in the context of other users' browsers, potentially allowing attackers to access sensitive project data, manipulate repository contents, or escalate their privileges further. The flaw essentially creates a trust boundary violation where user input intended for legitimate application functionality becomes a vector for malicious code delivery. This vulnerability represents a significant risk to organizations that rely on GitLab for version control and collaborative development environments, as it allows attackers to exploit the trust relationship between users and the platform.
Organizations affected by this vulnerability should immediately implement several mitigation strategies to protect their GitLab installations. The most critical immediate action involves upgrading to the patched versions mentioned in the advisory, specifically 18.11.7, 19.0.4, and 19.1.2, which contain proper input sanitization mechanisms. Additionally, organizations should implement comprehensive monitoring of user activities, particularly those with developer permissions, to detect unusual behavior patterns that might indicate exploitation attempts. Network-level controls including web application firewalls and content filtering systems can provide additional layers of protection by identifying and blocking suspicious script injection attempts. Regular security audits of user permissions and access controls should be conducted to ensure that only necessary users maintain developer roles, reducing the attack surface available to potential exploiters. The remediation process should also include comprehensive user education regarding safe coding practices and the importance of validating all external inputs before processing them within web applications, aligning with security best practices outlined in ISO/IEC 27001 and NIST SP 800-171 standards for secure software development lifecycle management.