CVE-2026-15004 in FileBird Plugin
Summary
by MITRE • 09/18/2026
The FileBird – WordPress Media Library Folders & File Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via image alt text in all versions up to, and including, 6.5.6 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/18/2026
The FileBird plugin, widely utilized within the WordPress ecosystem to enhance media library organization through folder structures and file management capabilities, contains a critical security flaw identified as Stored Cross-Site Scripting. This vulnerability affects all versions up to and including 6.5.6 and stems from insufficient input sanitization and output escaping mechanisms when handling image metadata. Specifically, the defect resides in how the plugin processes the alt text attribute associated with uploaded images. When an administrator or user with elevated privileges uploads media files, the system fails to adequately validate or escape special characters within the alt text field before storing it in the database and subsequently rendering it on public-facing pages. This lack of rigorous data validation allows malicious actors to inject executable JavaScript code directly into the page content by embedding script tags or event handlers within the image description fields.
The operational impact of this vulnerability is significant due to its stored nature, meaning that once the malicious payload is injected via an uploaded image's alt text, it persists in the database and executes automatically every time a user views the affected page. Unlike reflected XSS attacks which require tricking users into clicking specific links, stored vulnerabilities ensure widespread exposure as any visitor loading the compromised content will trigger the script execution within their browser context. This persistence transforms the vulnerability from a transient risk into a long-term threat vector that can compromise numerous sessions and potentially lead to persistent account takeovers if combined with other attack vectors such as session hijacking or credential theft through keyloggers embedded in the injected scripts.
The exploitation of this flaw requires authenticated access, specifically at least Author-level privileges within WordPress. This requirement limits the pool of potential attackers compared to unauthenticated vulnerabilities but does not mitigate the severity for organizations where internal trust boundaries are compromised or when insider threats exist. An attacker with these permissions can easily upload an image containing malicious JavaScript in its alt text field. Once saved, this payload becomes part of the site's content structure and will be served to all subsequent visitors who load pages displaying that specific media item. The execution context is typically within the same origin as the WordPress installation, granting the injected script full access to cookies, local storage, DOM elements, and administrative functions if the viewing user has higher privileges than the attacker.
From a classification perspective, this vulnerability aligns with CWE-79 Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific mechanism involves failure to sanitize input during data entry (CWE-610) and insufficient escaping when outputting data to web pages (CWE-80). In terms of the MITRE ATT&CK framework, this behavior corresponds to T1189 Drive-by Client Side Code Execution where attackers use compromised websites or legitimate sites with vulnerabilities to deliver malicious code. The attack chain typically involves initial access through valid credentials followed by persistence via stored payloads and execution in the victim's browser environment leading to potential credential theft or further lateral movement within the web application infrastructure.
Mitigation strategies must address both immediate remediation and long-term security hygiene. The most effective solution is to upgrade the FileBird plugin to version 6.5.7 or later where these input validation and output escaping issues have been resolved by the developers. For organizations unable to patch immediately, implementing a Web Application Firewall with rules capable of detecting and blocking XSS payloads in image metadata fields can provide temporary protection. Additionally, enforcing strict Content Security Policy headers that restrict script execution sources can mitigate the impact of successful injection attempts by preventing unauthorized scripts from running even if they are embedded in page content. Regular security audits focusing on media handling components and ensuring that all plugins adhere to WordPress coding standards for data sanitization will further reduce exposure to similar vulnerabilities across the entire CMS environment.