CVE-2026-80440 in Hustle Plugin
Summary
by MITRE • 09/09/2026
The Hustle WordPress plugin before 7.8.14.2 does not prevent shortcodes in submitted form values from being executed when it substitutes those values into the message it returns after submission, because the guard it applies can be defeated by nesting, allowing unauthenticated users to run any shortcode registered on the site.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified in versions of the Hustle WordPress plugin prior to 7.8.14.2 represents a critical server-side code execution risk stemming from improper input validation and output encoding practices. Specifically, the flaw resides within the mechanism that processes user-submitted form data for inclusion in automated email messages or notification templates. When a visitor submits a contact or lead generation form managed by Hustle, the plugin takes the raw values entered into those fields and substitutes them directly into the message body before sending it to the designated recipient addresses. The security control intended to mitigate this risk involves a guard designed to detect and neutralize shortcode syntax within these submitted values. However, this defensive measure is fundamentally flawed because it relies on simple pattern matching that can be bypassed through input nesting techniques.
The technical core of this vulnerability lies in how the plugin attempts to sanitize user input before rendering it into an email template. WordPress shortcodes are powerful features that allow developers and site administrators to embed dynamic content or execute specific functions using bracket notation, such as [shortcode_name]. The Hustle plugin implements a check to identify these brackets and prevent their execution within form fields to avoid potential security issues. Unfortunately, the implementation of this guard is insufficient against nested inputs. An attacker can craft a payload where shortcodes are embedded inside other strings or structures in a way that evades the initial detection logic. For instance, by manipulating the encoding or structure of the input string, an unauthenticated user can cause the system to interpret and execute arbitrary shortcodes registered on the WordPress installation during the message generation phase. This effectively allows remote code execution within the context of the web server process, as many plugins register shortcodes that perform sensitive operations such as database queries, file access, or administrative actions.
From an operational impact perspective, this vulnerability poses a severe threat to website integrity and data confidentiality. Because the attack vector is unauthenticated, any internet user can exploit it without needing valid credentials. The ability to execute arbitrary shortcodes means attackers can potentially extract sensitive information from the database, such as user details or configuration settings, by invoking shortcodes that output internal data. Furthermore, if a registered shortcode allows for file manipulation or system commands, the attacker could achieve full control over the web server environment. This leads to potential defacement of the website, installation of backdoors, and use of the compromised host for further malicious activities such as distributed denial-of-service attacks or phishing campaigns against other users. The impact is compounded by the fact that email notifications are often sent to site administrators with elevated privileges; thus, even if the immediate execution does not compromise the server directly, it could lead to credential theft via social engineering embedded in the generated emails.
This vulnerability aligns closely with CWE-79, which covers Cross-Site Scripting (XSS), although in this specific context, it manifests as Server-Side Code Execution due to the processing of shortcodes on the backend before email dispatch. It also relates to CWE-20, Improper Input Validation, as the plugin fails to adequately sanitize or validate user-supplied data against expected formats and safe character sets. In terms of the MITRE ATT&CK framework for enterprise security, this flaw facilitates Initial Access through exploitation of a web application vulnerability and potentially Privilege Escalation if the executed shortcodes leverage administrative capabilities. The attack vector is classified as Network-based with no additional privileges required, making it highly exploitable by automated tools found in the wild.
To mitigate this risk, organizations running Hustle must immediately update to version 7.8.14.2 or later, where the input validation logic has been hardened to properly handle nested inputs and enforce strict output encoding principles. Until an upgrade is possible, administrators should consider disabling shortcodes within form fields if such functionality is not strictly required for business operations. Additionally, implementing a Web Application Firewall can provide a layer of defense by blocking requests containing suspicious shortcode patterns or malformed input structures that resemble exploitation attempts. Regular security audits and penetration testing focused on form handling mechanisms are recommended to identify similar vulnerabilities in other plugins or custom code within the WordPress ecosystem. Monitoring server logs for unusual activity related to email generation processes may also help detect ongoing exploitation attempts early.