CVE-2026-76931 in Zephyr Project Manager Plugin
Summary
by MITRE • 09/08/2026
The Zephyr Project Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘message’ parameter in all versions up to, and including, 3.3.205 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Custom-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The vulnerability can only be exploited when the 'Directly link to project' plugin setting is disabled.
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Analysis
by VulDB Data Team • 09/08/2026
The Zephyr Project Manager plugin for WordPress represents a significant attack surface within enterprise content management environments, particularly given its role in facilitating agile development workflows and team collaboration. A critical security flaw has been identified in versions up through 3.3.205 that allows for Stored Cross-Site Scripting, commonly referred to as persistent XSS. This vulnerability stems from insufficient input sanitization and a lack of proper output escaping when handling the message parameter within the plugin's architecture. Unlike reflected XSS attacks which require immediate user interaction with a crafted link, stored vulnerabilities persist on the target server, making them more dangerous because they affect every user who views the compromised content without needing further manipulation by the attacker after the initial injection.
The technical root cause lies in how the application processes and renders data submitted through the message parameter. When an authenticated user submits this data, the system fails to adequately filter out malicious script tags or event handlers before storing them in the database. Subsequently, when this stored content is retrieved for display on project pages, it is rendered directly into the HTML output without encoding special characters such as less-than and greater-than signs. This failure allows an attacker with Custom-level access permissions or higher to inject arbitrary JavaScript code that becomes part of the page structure itself. The persistence of this payload means that any subsequent user accessing these specific project views will have their browser execute the injected scripts, potentially leading to session hijacking, credential theft via keyloggers, defacement, or redirection to malicious sites.
The operational impact of this vulnerability is severe due to its potential for widespread compromise within an organization's collaborative workspace. Since Zephyr Project Manager is often used by development teams and project managers who frequently interact with the platform, a successful exploitation could lead to the compromise of multiple user accounts if session cookies are stolen via JavaScript execution in the context of the vulnerable domain. This can result in unauthorized access to sensitive project data, intellectual property theft, or further lateral movement within the network infrastructure depending on how tightly integrated WordPress is with other internal systems. The requirement for authenticated access limits the pool of potential attackers but does not mitigate the severity once an account with sufficient privileges is compromised through phishing, credential stuffing, or other means.
It is important to note that this specific vector requires a particular configuration state within the plugin settings. The vulnerability can only be exploited when the Directly link to project setting is disabled. This constraint suggests that the vulnerable code path is tied to how embedded content or internal links are rendered rather than external direct access points. Administrators should verify their current configuration status as part of their immediate response, although relying solely on this setting being enabled is not a robust long-term security strategy given the underlying lack of input validation and output encoding in the software itself.
To mitigate this risk, organizations must immediately update the Zephyr Project Manager plugin to version 3.3.206 or later where these sanitization issues have been addressed by the vendor. In addition to patching, administrators should enforce strict least-privilege principles regarding WordPress user roles, ensuring that only trusted individuals hold Custom-level access and above. Implementing a Web Application Firewall with robust XSS detection rules can provide an additional layer of defense by blocking malicious payloads before they reach the application logic. Furthermore, enabling Content Security Policy headers on the web server can help mitigate the impact of any successful exploitation by restricting the sources from which scripts are allowed to execute, thereby reducing the effectiveness of injected JavaScript even if it manages to bypass input filters.
From a classification perspective, this vulnerability aligns with CWE-79 Improper Neutralization of Input During Web Page Generation known as Cross-site Scripting and specifically falls under the sub-category of Stored XSS. In terms of adversary tactics, this maps to ATT&CK technique T1059 Command and Control via Application Layer Protocol or more broadly to initial access vectors involving compromised credentials leading to persistent presence within a web application environment. Understanding these mappings helps in aligning remediation efforts with broader security frameworks and ensures that the fix addresses not just the immediate code defect but also contributes to overall resilience against similar injection-based attacks across the organization's digital assets.