CVE-2026-104937 in Shopware
Summary
by MITRE • 10/13/2026
Shopware version 6.7 allows the upload of attacker‑controlled HTML files and serves them as text/html without effective security headers, enabling stored cross-site scripting (XSS). When a malicious uploaded file containing an embedded JavaScript payload is viewed by an administrator, the attacker can access and exfiltrate the administrator's authentication token.
The compromised token enables unauthorized access to the Shopware Administration API. If the affected administrator account possesses extension‑management privileges, an attacker can upload, install, and activate malicious plugins to achieve arbitrary PHP code execution on the underlying OS with the privileges of the Shopware process.
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Analysis
by VulDB Data Team • 10/13/2026
Shopware version 6.7 contains a critical vulnerability related to file upload handling that allows for stored cross-site scripting attacks through improper validation of uploaded content types. The system permits users to upload files containing HTML markup, which are subsequently served by the web server with a Content-Type header indicating text/html rather than treating them as static binary data or plain text. This misconfiguration bypasses standard browser security mechanisms such as MIME type sniffing protections and allows embedded JavaScript payloads within these uploaded documents to execute in the context of any user who views the file through the administrative interface. The flaw stems from insufficient sanitization of file extensions and content types during the upload process, combined with a lack of effective security headers like Content-Security-Policy that would otherwise restrict script execution origins or block inline scripts.
The operational impact of this vulnerability is severe due to its stored nature, meaning the malicious payload persists on the server until manually removed. When an administrator accesses the compromised file through the Shopware administration panel, their browser executes the embedded JavaScript code within the trusted domain context. This allows attackers to perform session hijacking by stealing authentication tokens and cookies associated with the administrative account. The stolen credentials provide immediate unauthorized access to the Shopware Administration API, which serves as a primary interface for managing store configurations, products, orders, and system settings. Because the attack targets high-privilege accounts, the potential scope of damage extends beyond simple data theft to complete compromise of the e-commerce platform's integrity and availability.
The consequences escalate significantly if the compromised administrator account holds extension-management privileges. In such scenarios, an attacker can leverage the stolen authentication token to upload, install, and activate malicious plugins within the Shopware ecosystem. These custom extensions are executed with the same permissions as the underlying web server process, typically running under a dedicated system user but still possessing significant access to application files and database connections. Through carefully crafted plugin code written in PHP, an attacker can achieve arbitrary remote code execution on the host operating system. This capability allows for full system compromise, including data exfiltration, installation of backdoors, lateral movement within internal networks, and disruption of business operations by modifying or deleting critical store data.
This vulnerability aligns with CWE-79 Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting, specifically in the context of stored XSS where malicious scripts are permanently stored on target servers. Additionally, it relates to CWE-434 Unrestricted Upload of File with Dangerous Type and CWE-20 Improper Input Validation regarding file extension and content-type verification failures. From a tactical perspective, this attack path maps to MITRE ATT&CK techniques including T1505.003 Web Shell: ASPX, T1505.002 Web Shell: PHP, and T1078 Valid Accounts for initial access via stolen credentials. The exploitation chain demonstrates how a seemingly minor input validation flaw can lead to complete system compromise through privilege escalation within the application layer.
Mitigation strategies must address both immediate remediation and long-term security hardening. Shopware users should immediately apply available patches that enforce strict file type restrictions, ensuring only expected image formats are accepted for user uploads while rejecting HTML or executable files at the upload stage rather than relying on client-side checks. Implementing a Content-Security-Policy header with directives such as script-src 'self' can mitigate XSS impacts even if malicious content is served incorrectly by restricting where scripts can execute from. Additionally, administrators should enforce principle of least privilege by separating extension management permissions among multiple users to limit the blast radius of any single compromised account. Regular security audits and penetration testing focused on file upload mechanisms are essential to identify similar vulnerabilities across other modules within the platform infrastructure.