Overview
Recently, a potentially devastating vulnerability, identified as CVE-2025-7739, was discovered in GitLab CE/EE. This vulnerability affects all versions from 18.2 before 18.2.2. The issue pertains to stored cross-site scripting (XSS), a serious security flaw that can allow authenticated users to inject malicious HTML content into scoped label descriptions under certain conditions. This can lead to potential system compromise or data leakage, posing significant risks to both data integrity and user privacy.
Vulnerability Summary
CVE ID: CVE-2025-7739
Severity: High (8.7 CVSS Score)
Attack Vector: Web-based
Privileges Required: User
User Interaction: Required
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
GitLab CE | 18.2 before 18.2.2
GitLab EE | 18.2 before 18.2.2
How the Exploit Works
The exploit takes advantage of a flaw in the handling of scoped label descriptions in GitLab CE/EE. An attacker with user-level privileges, under certain conditions, can inject malicious HTML content into these descriptions. When these descriptions are rendered by a web browser, the malicious code is executed, potentially compromising the system or leaking sensitive data.
Conceptual Example Code
Here’s a high-level example of how an attacker might exploit this vulnerability:
POST /api/v4/projects/1/labels HTTP/1.1
Host: gitlab.example.com
Content-Type: application/json
Authorization: Bearer <User-Token>
{
"name": "legitimate_label",
"color": "#0033CC",
"description": "<img src=x onerror=alert('XSS')>"
}In this example, the attacker is creating a new label. The description contains an image tag with a non-existent source (x), triggering the ‘onerror’ event, which executes a JavaScript ‘alert’ function. In a real-world scenario, the malicious script could carry out more harmful actions, such as stealing session cookies or performing actions on behalf of the user.
Mitigation Guidance
The most straightforward way to address this vulnerability is by applying the vendor-supplied patch. This patch corrects the flaw within the label description handling, preventing the execution of injected HTML. For those who cannot immediately apply the patch, using a web application firewall (WAF) or intrusion detection system (IDS) can offer temporary mitigation by detecting and blocking attempts to exploit this vulnerability.
Nevertheless, it’s important to apply the patch as soon as possible to fully resolve the issue, as relying on WAFs or IDS systems may not provide complete protection against all potential exploitation techniques.