CVE-2026-3093 in GitLab
Summary
by MITRE • 07/29/2026
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 14.0 before 19.0.5, 19.1 before 19.1.3, and 19.2 before 19.2.1 that under certain conditions could have allowed an attacker to execute arbitrary JavaScript in another user's browser via a crafted URL, due to improper sanitization of user-controlled input.
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Analysis
by VulDB Data Team • 07/29/2026
This vulnerability represents a critical cross-site scripting flaw that affects GitLab community and enterprise editions across multiple version ranges including 14.0 through 19.0.4, 19.1 through 19.1.2, and 19.2 through 19.2.0. The security issue stems from inadequate input validation and sanitization mechanisms within GitLab's processing of user-controlled data. When users encounter specially crafted URLs containing malicious javascript payloads, the application fails to properly sanitize these inputs before rendering them in the browser context, creating an environment where attackers can inject arbitrary code execution commands. This vulnerability directly maps to CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') which is a fundamental web security weakness classified under the OWASP Top Ten as one of the most prevalent and dangerous application security risks.
The operational impact of this vulnerability extends beyond simple code injection as it enables attackers to execute malicious scripts within the context of other users' browsers, potentially leading to session hijacking, credential theft, data exfiltration, or complete account compromise. Attackers could craft deceptive URLs that appear legitimate but contain hidden javascript payloads designed to exploit the sanitization flaw. Once executed, these scripts could access user sessions, modify repository contents, read sensitive information, or perform actions on behalf of authenticated users without their knowledge. The vulnerability is particularly dangerous in enterprise environments where GitLab serves as a central collaboration platform for development teams and where users may have elevated privileges within projects and repositories.
Security professionals should implement immediate mitigations including ensuring all affected GitLab instances are updated to the latest patched versions, implementing web application firewalls to detect and block suspicious URL patterns, and conducting comprehensive security audits of user-generated content handling mechanisms. Organizations should also consider network-level protections such as content security policies that restrict script execution from untrusted sources and implement strict input validation for all user-controllable parameters. The remediation process requires thorough testing of the updated systems to ensure that the patch does not introduce regressions in legitimate functionality while maintaining the integrity of user experience. This vulnerability aligns with several ATT&CK techniques including T1566 - Phishing and T1059 - Command and Scripting Interpreter, demonstrating how initial access through malicious URLs can escalate into full system compromise through client-side exploitation.