CVE-2026-110525 in MCB Plugin
Summary
by MITRE • 11/06/2026
The MCB WordPress plugin through 1.0.0 does not sanitise or escape request header values before storing them and later rendering them in the administrator statistics grid, allowing unauthenticated attackers to store malicious JavaScript that executes in an administrator's browser session when the statistics page is viewed.
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Analysis
by VulDB Data Team • 11/06/2026
The vulnerability identified in the MCB WordPress plugin version 1.0.0 represents a critical server-side request header injection flaw that leads directly to stored cross-site scripting. This security defect stems from a fundamental failure in input validation and output encoding mechanisms within the application's backend logic. Specifically, the software accepts HTTP request headers without performing any sanitization or escaping procedures before persisting these values into its local database storage. By treating untrusted header data as safe for long-term retention, the plugin creates a persistent vector for malicious code injection that does not require user interaction to trigger initially but requires administrative access to execute fully.
The technical mechanism of this exploit relies on the attacker crafting specific HTTP requests with manipulated headers containing executable JavaScript payloads. When these malformed requests are processed by the vulnerable application, the raw header content is written directly into the database without any transformation or filtering. This behavior violates fundamental web security principles regarding the handling of untrusted data sources. The flaw aligns closely with CWE-79, which classifies improper neutralization of input during web page generation as a primary category for cross-site scripting vulnerabilities. Furthermore, because the injection occurs via HTTP headers rather than standard form fields or URL parameters, it may bypass certain basic security monitoring tools that focus on query string and body parameter analysis, making detection more challenging without specialized logging inspection capabilities.
The operational impact of this vulnerability is severe due to its stored nature combined with an unauthenticated attack vector. An attacker does not need valid credentials to inject the malicious script into the system's database. However, the payload remains dormant until a privileged user, specifically an administrator, accesses the statistics grid page where the unsanitized header data is rendered. Upon viewing this administrative interface, the browser interprets the stored JavaScript as part of the webpage content and executes it within the context of the admin session. This execution environment grants the malicious script full access to all cookies, local storage, and DOM elements associated with the WordPress administration area, effectively allowing the attacker to hijack the administrator's active session.
This scenario maps directly to several tactics in the MITRE ATT&CK framework for enterprise security. The initial injection phase corresponds to T1059 Command and Scripting Interpreter through browser-based execution, while the persistence mechanism aligns with stored XSS techniques often categorized under data manipulation or supply chain compromise vectors depending on deployment context. The exploitation of administrative privileges places this vulnerability in a high-severity category because it facilitates complete system takeover. Once the attacker gains control via session hijacking, they can modify site configurations, install additional backdoors, exfiltrate sensitive database contents, and potentially pivot to other systems within the network infrastructure that trust the compromised WordPress instance.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The most effective solution is to apply a software update provided by the plugin vendor if one exists, as this should include proper input validation and output encoding routines. In cases where an official patch is unavailable or delayed, administrators can implement web application firewall rules that inspect HTTP headers for common script injection patterns such as angle brackets, quotes, and event handler attributes like onerror or onload. Additionally, enforcing strict Content Security Policy directives via the X-Content-Security-Policy header can significantly reduce the impact of any successful XSS execution by restricting script sources to trusted domains only. Developers should also adopt a defense-in-depth approach by ensuring that all data rendered in HTML contexts is properly encoded using context-aware escaping techniques specific to HTML body, attribute, or JavaScript string environments as defined in OWASP guidelines.