A vulnerability identified as CVE-2018-17536 was discovered in GitLab Community and Enterprise Edition versions prior to 11.1.7, 11.2.x before 11.2.4, and 11.3.x before 11.3.1. The issue exposes users to a stored Cross-Site Scripting (XSS) attack on the merge request page via project import. This blog post aims to provide an in-depth understanding of the vulnerability, its potential impact, and how to protect your GitLab instance from being exploited.


Cross-Site Scripting (XSS) is a type of insecure coding practice that enables attackers to inject malicious scripts into webpages viewed by other users. A stored XSS attack, also known as persistent or second-order XSS attack, occurs when the malicious script is stored on the target server, such as in a database or a comment field. The script is then executed by the victim's browser when they visit the affected webpage.

In the context of CVE-2018-17536, an attacker can exploit the vulnerability to store a malicious script within GitLab's merge request page via project import. Once the script is stored, any user visiting the merge request page will have the malicious script executed on their browser.

For more detailed information about CVE-2018-17536, consider checking the following official sources

- GitLab Advisory: [https://about.gitlab.com/releases/2018/09/28/security-release-gitlab-11-dot-3-dot-1-released/#cve-2018-17536-stored-xss-on-merge-request-via-project-import]()
- CVE Details: [https://www.cvedetails.com/cve/CVE-2018-17536/]()

Code Snippet

The vulnerability resides in the way GitLab handles project imports. An attacker could craft a malicious project file with an embedded script, such as:


When a victim imports this malicious project, the script gets stored in the merge request page and executed whenever the page is loaded by other users.

Exploitation Details

For an attacker to successfully exploit the CVE-2018-17536 vulnerability, the following conditions must be met:

The attacker must have access to create or import a project on the targeted GitLab instance.

2. The attacker must convince a victim to import the malicious project or navigate to the affected merge request page.

Mitigation Steps

To protect your GitLab instance from being exploited through CVE-2018-17536, it is recommended to upgrade to one of the following fixed versions:

GitLab Community Edition (CE) and Enterprise Edition (EE) 11.3.1

To upgrade your GitLab server, visit the official GitLab documentation for detailed instructions: [https://docs.gitlab.com/ee/policy/maintenance.html#upgrading-guide]().


CVE-2018-17536 represents a stored XSS vulnerability in GitLab that can expose users to potential attacks via the merge request page through project import. It is essential to upgrade your GitLab instance to the most recent patched version to protect against this threat. By following industry best practices, monitoring for security patches, and keeping your software up-to-date, you reduce the risk of exploitation and maintain a secure GitLab environment.


Published on: 04/15/2023 23:15:00 UTC
Last modified on: 04/25/2023 19:15:00 UTC