CVE-2026-77129 in Event management and registration Plugin
Summary
by MITRE • 08/25/2026
The extension passes an editor-configurable email subject string directly into a Fluid template source without restriction. A backend user with edit access to the event plugin or Backend Module can supply Fluid ViewHelper syntax in this field to disclose sensitive data or execute TypoScript content objects. Exploitation of this issue requires an authenticated backend account with edit access to the event registration plugin or backend module.
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Analysis
by VulDB Data Team • 08/25/2026
The vulnerability described constitutes a Server-Side Template Injection (SSTI) flaw within a TYPO3 extension, specifically targeting the Fluid templating engine used for rendering user interfaces in both frontend and backend contexts. The core technical deficiency lies in the insecure handling of an editor-configurable email subject string field. Instead of sanitizing or escaping this input before it is processed by the template engine, the application passes the raw value directly into a Fluid template source. This architectural oversight allows any data entered into this specific configuration field to be interpreted as executable code rather than static text content. In modern web development frameworks like TYPO3, separating logic from presentation is critical for security; however, in this instance, user-controlled input breaches that boundary by becoming part of the execution context of the template engine itself.
Fluid templates utilize a syntax involving ViewHelpers which are essentially PHP classes invoked within the template to perform various operations such as data manipulation, URL generation, or accessing backend services. When an attacker injects Fluid ViewHelper syntax into the email subject field, they effectively trick the server-side rendering process into executing these ViewHelpers with arbitrary parameters. This capability transforms a simple configuration error into a potent code execution vector. The impact is severe because it allows for unauthorized access to sensitive data stored within the TYPO3 backend or even remote code execution depending on the specific ViewHelper invoked and the permissions of the exploiting user account. For instance, an attacker could potentially read files from the server filesystem, query database contents directly through SQL injection via template expressions, or trigger actions that modify system state.
The operational impact extends beyond mere data disclosure to include potential compromise of the entire TYPO3 installation if combined with other vulnerabilities or misconfigurations. An authenticated backend user possessing edit access to the event plugin or Backend Module becomes an effective attacker vector due to their elevated privileges within the application's permission model. This requirement highlights a common issue in web applications where trust boundaries are not strictly enforced between different roles and modules. The ability to execute TypoScript content objects further amplifies the risk, as TypoScript is a powerful configuration language that can interact deeply with the TYPO3 core, potentially leading to full system compromise if exploited correctly by an insider threat or a compromised account.
Mitigation strategies must focus on strict input validation and output encoding principles applied at multiple layers of the application stack. First, immediate patching of the extension is required to ensure that any user-supplied data intended for display in email subjects is strictly treated as plain text. This involves escaping special characters associated with Fluid syntax such as curly braces and double hashes before they reach the template engine. Additionally, implementing a whitelist approach for allowed characters in configuration fields can prevent injection attempts at an early stage. From a broader security architecture perspective, enforcing least privilege principles ensures that backend users do not have unnecessary edit access to modules containing vulnerable input fields unless absolutely required by their job function. Regular security audits and static code analysis tools configured to detect template injection patterns should also be integrated into the development lifecycle to prevent similar flaws in future releases.
This vulnerability aligns with CWE-94, which describes Improper Control of Generation of Code (Code Injection), specifically focusing on server-side template injection scenarios where user input influences the execution logic without proper sanitization. Furthermore, it maps to MITRE ATT&CK techniques related to Server-Side Request Forgery and potentially Command and Control if used for exfiltrating data or maintaining persistence through crafted requests. Understanding these mappings helps in categorizing the risk accurately within enterprise security frameworks and prioritizing remediation efforts based on standardized threat intelligence models rather than ad-hoc assessments.