CVE-2026-15604 in Companion Plugin
Summary
by MITRE • 08/16/2026
The Toocheke Companion plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 2.10 via the 'series_bg_color' post meta field. This is due to insufficient input sanitization in the toocheke_series_bg_color_save() function (which stores the raw $_POST value in post meta) and insufficient output escaping in the series admin column rendering (where the stored value is concatenated into a style attribute without esc_attr()). This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user, such as an administrator, accesses the series list table in the admin dashboard.
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Analysis
by VulDB Data Team • 08/18/2026
The Toocheke Companion plugin for WordPress presents a critical stored cross-site scripting vulnerability that affects versions up to and including 210. This security flaw resides in the plugin's handling of the 'series_bg_color' post meta field, creating a persistent threat vector within the WordPress administration interface. The vulnerability stems from inadequate input validation and output sanitization practices within the plugin's codebase, specifically manifesting in two distinct code paths that together enable malicious script execution.
The technical implementation of this vulnerability occurs through the toocheke_series_bg_color_save() function which directly stores raw $_POST values into post meta without proper sanitization. This function fails to validate or filter the incoming color value before persistence, allowing potentially malicious input to be saved in the database. Subsequently, during the rendering of series admin columns, the stored value is concatenated into HTML style attributes without appropriate escaping through esc_attr() function. This dual failure creates a classic stored XSS scenario where attacker-controlled content flows from user input directly into rendered HTML output.
Authenticated attackers with contributor-level privileges or higher can exploit this vulnerability by navigating to the series edit screen and injecting malicious JavaScript code through the color selection field. When administrators view the series list table in the admin dashboard, the malicious script executes within their browser context, potentially enabling session hijacking, data exfiltration, or further privilege escalation attacks. The impact extends beyond simple script execution as this vulnerability can be leveraged for more sophisticated attacks including credential theft and malware distribution.
This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and maps to ATT&CK technique T1566.001 related to spearphishing attachments. The attack surface is particularly concerning as it targets the WordPress admin interface where privileged users frequently access, making it an attractive vector for attackers seeking to compromise administrator accounts. The exploitation requires minimal user interaction beyond normal administrative tasks, increasing the likelihood of successful compromise.
Security mitigations should include immediate code patches that implement proper input validation using wp_kses() or similar sanitization functions before storing post meta values. Output escaping must be enforced through esc_attr() when rendering stored values into HTML attributes, following WordPress core security guidelines. Additionally, administrators should implement role-based access controls limiting contributor privileges where possible, and monitor for unusual activity in the series management section. Regular security audits of plugin code should verify proper sanitization practices and adherence to WordPress security coding standards to prevent similar vulnerabilities from emerging in other components.