CVE-2026-80517 in WP Ultimate CSV Importer Plugin
Summary
by MITRE • 10/03/2026
The WP Ultimate CSV Importer WordPress plugin before 9.2 does not properly validate the file types contained in an uploaded archive nor sanitise their content before storing them in a publicly served location, allowing high privilege users such as administrators to achieve Stored Cross-Site Scripting. On Multisite installations a site Administrator does not hold the unfiltered_html capability, so this lets them run scripts in the session of users who view the file, including Network Super Admins.
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Analysis
by VulDB Data Team • 10/03/2026
The vulnerability identified in WP Ultimate CSV Importer versions prior to 9.2 represents a critical security flaw rooted in inadequate input validation and sanitization mechanisms for uploaded archive files. The core technical issue lies in the plugin's failure to rigorously verify file types within archives submitted by users, combined with insufficient cleaning of content before storage. When an administrator uploads a compressed archive containing malicious scripts disguised as legitimate data or configuration files, the system accepts these inputs without adequate scrutiny. These files are then stored in directories that are publicly accessible via HTTP requests, effectively placing attacker-controlled code directly into the web server's document root where it can be executed by any visitor with access to the specific file path.
This architectural weakness facilitates Stored Cross-Site Scripting attacks, a severe threat classified under CWE-80 and mapped within the MITRE ATT&CK framework as T1505.003 for Server Side Web Application Components. Unlike reflected XSS which requires immediate user interaction with a crafted link, stored XSS persists on the server side, ensuring that every time an authorized or unauthorized user accesses the compromised file through their browser session, the malicious JavaScript payload executes automatically within the context of that site. This persistence transforms a single upload into a long-term attack vector capable of compromising multiple users over time without further interaction from the initial attacker.
The impact is particularly acute on WordPress Multisite installations due to specific capability restrictions applied to individual site administrators. In such environments, standard site administrators are explicitly denied the unfiltered_html capability by default as a security measure to prevent them from injecting raw HTML or script tags through normal content editing interfaces. However, this plugin bypasses those protections because it does not apply the same sanitization filters during the archive import process that are applied to post content or widget inputs. Consequently, an individual site administrator can exploit this gap to inject malicious scripts that will execute in the browser sessions of other users visiting the affected pages.
The severity escalates significantly when considering Network Super Administrators who manage entire multisite networks. If a lower-privileged site administrator successfully exploits this vulnerability, they can trigger script execution within the session context of high-privilege accounts such as Network Super Admins. This effectively allows privilege escalation from a standard site admin to full network control without needing valid credentials for those higher-level roles. The attacker gains the ability to manipulate administrative interfaces, exfiltrate sensitive database information, or install further backdoors by leveraging the trust relationship between the victim's browser session and the WordPress administration dashboard.
Mitigation strategies must focus on immediate remediation through software updates and enhanced configuration practices. Administrators running affected versions of WP Ultimate CSV Importer should upgrade to version 9.2 or later where these validation checks have been strengthened. Until an update is applied, it is advisable to restrict file upload capabilities for all users except the most trusted network administrators if possible. Additionally, implementing a Web Application Firewall with rules specifically targeting suspicious patterns in uploaded archive contents and enforcing strict Content Security Policy headers can help mitigate the impact of any successfully injected scripts by preventing their execution or limiting their scope within the browser environment. Regular auditing of plugin code against current security standards remains essential to prevent similar flaws from persisting in future releases.