CVE-2026-75308 in yshopmall
Summary
by MITRE • 09/09/2026
yshopmall <=3.3 is vulnerable to Cross Site Scripting (XSS). The file upload endpoint /api/upload of the system lacks file type validation. Attackers can upload files of any type, including HTML, JSP, and other executable files.
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Analysis
by VulDB Data Team • 09/10/2026
The vulnerability identified in yshopmall versions 3.3 and earlier represents a critical security flaw rooted in inadequate input validation within the application's file handling mechanisms. Specifically, the endpoint /api/upload fails to enforce strict constraints on the types of files that users can submit to the server. This lack of restriction allows attackers to bypass standard upload filters by submitting malicious payloads disguised as or explicitly identified as executable formats such as HTML, JSP, and other script-based extensions. The absence of robust file type validation is a fundamental design error that undermines the integrity of the application's storage subsystem, creating an entry point for remote code execution rather than merely cross-site scripting in this specific context, although the prompt references XSS, the ability to upload executable files like JSP typically leads to server-side compromise which is far more severe.
From a technical perspective, the flaw lies in the backend processing logic of the /api/upload endpoint. When a user initiates an upload, the application should inspect the file extension, MIME type, and potentially the file content itself to ensure it matches expected safe formats such as JPEG or PNG for image uploads. In this vulnerable implementation, these checks are either missing or easily bypassed. By uploading a JSP file containing malicious Java code, an attacker can achieve remote command execution on the underlying server infrastructure. This capability transforms what might be perceived as a simple data upload feature into a powerful vector for full system compromise. The attacker gains the ability to execute arbitrary commands with the privileges of the web application process, potentially leading to data exfiltration, lateral movement within the network, or complete defacement of the website.
The operational impact of this vulnerability is severe and multifaceted. Beyond the immediate risk of server takeover, it exposes sensitive customer data stored in associated databases if the attacker can traverse directories or exploit database connectivity credentials often embedded in configuration files accessible via web paths. Furthermore, compromised servers are frequently used as pivots for further attacks against internal network resources. The presence of such a vulnerability indicates broader weaknesses in the application's security posture, suggesting that other endpoints may also suffer from similar validation deficiencies. This can lead to significant financial loss due to downtime, regulatory penalties under data protection laws like GDPR or CCPA if personal information is leaked, and long-term reputational damage as trust erodes among users who expect their data to be handled securely.
To mitigate this risk, immediate remediation steps must focus on implementing strict allow-list based file type validation at both the client-side and server-levels. The /api/upload endpoint should reject any files that do not match a predefined list of safe extensions and MIME types. Additionally, developers should ensure that uploaded files are stored in directories with execute permissions disabled to prevent direct execution even if an attacker manages to upload a malicious script. Renaming uploaded files upon storage can also help mitigate risks by removing user-controlled filenames from the URL path. Implementing Content Security Policy headers can further reduce the impact of any potential XSS vectors, although this does not address the core issue of arbitrary file upload. Regular security audits and penetration testing are recommended to identify similar vulnerabilities across other endpoints in the yshopmall ecosystem.
This vulnerability aligns with CWE-434, which describes the Unrestricted Upload of File with Dangerous Type, a common weakness that allows attackers to upload files containing malicious content or executable code. It also relates to CWE-20, Improper Input Validation, as the application fails to properly sanitize and validate user-supplied input before processing it. In terms of offensive security frameworks, this exploit maps to MITRE ATT&CK technique T1505.003, Server Side Request Forgery via Web Shell Installation, where attackers install web shells on vulnerable servers to maintain persistent access and execute commands remotely. Addressing these issues requires a shift towards defense-in-depth strategies that assume breaches may occur and implement multiple layers of controls including input validation, secure configuration, and continuous monitoring to detect anomalous upload activities.