CVE-2026-6335: XSS in GitLab 18.11
Platform
gitlab
Component
gitlab
Fixed in
18.11.3
CVE-2026-6335 is a Cross-Site Scripting (XSS) vulnerability affecting GitLab Community Edition (CE) and Enterprise Edition (EE). This flaw allows an authenticated user, under specific conditions, to execute arbitrary code within the browser session of another user. The vulnerability impacts GitLab versions 18.11.0 through 18.11.3, and a fix is available in version 18.11.3.
Impact and Attack Scenarios
Successful exploitation of CVE-2026-6335 could allow an attacker to impersonate another user within GitLab, potentially gaining access to sensitive data or performing actions on their behalf. This could include viewing private repositories, modifying project settings, or even accessing administrative functions if the targeted user possesses elevated privileges. The impact is amplified if the targeted user has access to critical infrastructure or sensitive data, leading to a broader compromise of the GitLab instance. The ability to execute code within another user's browser session represents a significant security risk, as it bypasses traditional authentication mechanisms.
Exploitation Context
CVE-2026-6335 was published on 2026-05-14. As of this date, there are no publicly known active campaigns exploiting this vulnerability. No public Proof-of-Concept (POC) code has been released. The vulnerability is not listed on KEV (Kernel Exploit Vulnerability) and has a low EPSS (Exploit Prediction Scoring System) score, indicating a relatively low probability of exploitation in the wild.
Threat Intelligence
Exploit Status
CVSS Vector
What do these metrics mean?
- Attack Vector
- Network — remotely exploitable over the internet. No physical or local access required. Widest attack surface.
- Attack Complexity
- Low — no special conditions required. Attacker can exploit reliably without depending on rare configurations or timing.
- Privileges Required
- Low — any valid user account is sufficient. Basic authenticated access required.
- User Interaction
- Required — victim must take an action: open a file, click a link, or visit a crafted page.
- Scope
- Changed — successful attack can pivot beyond the vulnerable component to other systems or the host OS.
- Confidentiality
- Low — partial or indirect data access. Attacker gains limited information.
- Integrity
- Low — attacker can modify some data with limited scope or impact.
- Availability
- None — no availability impact. Service remains fully operational.
Affected Software
Weakness Classification (CWE)
Timeline
- Reserved
- Published
Mitigation and Workarounds
The primary mitigation for CVE-2026-6335 is to immediately upgrade GitLab to version 18.11.3 or later. If upgrading is not immediately feasible, consider implementing stricter input validation on user-supplied data within GitLab. While not a direct fix, this can help reduce the attack surface. Review GitLab's security configuration and ensure that all security features are enabled and properly configured. Monitor GitLab logs for any suspicious activity that might indicate exploitation attempts.
How to fix
Actualice GitLab a la versión 18.11.3 o posterior para mitigar la vulnerabilidad de Cross-Site Scripting (XSS). Esta actualización corrige la sanitización inadecuada de la entrada, previniendo la ejecución de código arbitrario en el navegador de otros usuarios.
Frequently asked questions
What is CVE-2026-6335 — XSS in GitLab 18.11?
CVE-2026-6335 is a Cross-Site Scripting (XSS) vulnerability in GitLab CE/EE versions 18.11.0 through 18.11.3. It allows an authenticated user to potentially execute code in another user's browser session.
Am I affected by CVE-2026-6335 in GitLab 18.11?
If you are running GitLab CE or EE versions 18.11.0, 18.11.1, 18.11.2, or 18.11.3, you are potentially affected by this vulnerability. Upgrade to 18.11.3 or later.
How do I fix CVE-2026-6335 in GitLab 18.11?
The recommended fix is to upgrade GitLab to version 18.11.3 or a later version. This patch addresses the improper sanitization issue.
Is CVE-2026-6335 being actively exploited?
As of 2026-05-14, there are no publicly known active campaigns exploiting this vulnerability, and no public POC code is available.
Where can I find the official GitLab advisory for CVE-2026-6335?
Refer to the official GitLab security advisory for CVE-2026-6335 on the GitLab website: [https://gitlab.com/security/advisories/](https://gitlab.com/security/advisories/)
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