CVE-2016-4056 in TYPO3
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Backend component in TYPO3 6.2.x before 6.2.19 allows remote attackers to inject arbitrary web script or HTML via the module parameter when creating a bookmark.
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Analysis
by VulDB Data Team • 05/14/2026
The CVE-2016-4056 vulnerability represents a critical cross-site scripting flaw within the TYPO3 content management system's backend component. This vulnerability specifically affects TYPO3 versions 6.2.x prior to 6.2.19, where the system fails to properly sanitize user input when processing the module parameter during bookmark creation. The flaw exists in the backend administrative interface, making it a significant concern for organizations relying on TYPO3 for their web content management needs. The vulnerability stems from inadequate input validation and output encoding mechanisms that should have prevented malicious scripts from being executed within the context of authenticated administrative sessions.
The technical implementation of this vulnerability allows remote attackers to inject arbitrary web scripts or HTML code through the module parameter field when creating bookmarks within the TYPO3 backend. This occurs because the application does not properly escape or validate user-supplied input before rendering it in the browser context. When an administrator creates a bookmark with malicious input in the module parameter, the crafted payload gets stored and subsequently executed in the browser of any user who views the bookmark or navigates to the affected module. The vulnerability is particularly dangerous because it operates within the administrative backend, where attackers can potentially gain elevated privileges and access sensitive system information. This flaw aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities due to insufficient input validation and output encoding.
The operational impact of CVE-2016-4056 extends beyond simple script injection, as it can enable attackers to perform a wide range of malicious activities within the TYPO3 environment. An attacker who successfully exploits this vulnerability could steal administrative session cookies, redirect users to malicious websites, modify content, or even execute arbitrary commands if the backend system has additional vulnerabilities. The attack vector is particularly concerning because it requires minimal user interaction beyond the creation of a malicious bookmark, and the effects can persist for extended periods until the bookmark is removed or the system is patched. This vulnerability directly impacts the integrity and confidentiality of the TYPO3 installation, potentially leading to complete system compromise if combined with other exploitation techniques. The threat landscape for this vulnerability aligns with ATT&CK technique T1059, which covers command and scripting interpreter usage, and T1566, which addresses credential access through social engineering.
Organizations affected by this vulnerability should immediately implement comprehensive patch management procedures to upgrade to TYPO3 6.2.19 or later versions where this vulnerability has been resolved. The fix involves implementing proper input sanitization and output encoding mechanisms that ensure all user-supplied data is properly escaped before being rendered in the backend interface. Additional mitigations include implementing web application firewalls to monitor and block suspicious requests, conducting regular security assessments of backend components, and establishing strict input validation policies for all administrative interfaces. Security teams should also consider implementing monitoring solutions that can detect anomalous bookmark creation patterns or unusual administrative activities that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing defense-in-depth strategies to protect administrative interfaces from persistent threats. Organizations should also review their access control policies to ensure that only authorized personnel have administrative privileges, reducing the potential impact of successful exploitation attempts.