CVE-2016-5091 in TYPO3
Summary
by MITRE
ExtbasE in TYPO3 4.3.0 before 6.2.24, 7.x before 7.6.8, and 8.1.1 allows remote attackers to obtain sensitive information or possibly execute arbitrary code via a crafted Extbase action.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/14/2026
The CVE-2016-5091 vulnerability represents a critical security flaw in the Extbase framework component of TYPO3 content management systems. This vulnerability affects multiple versions including TYPO3 4.3.0 through 6.2.23, 7.x versions prior to 7.6.8, and 8.1.0 and earlier releases. The flaw stems from insufficient input validation and sanitization within the Extbase action handling mechanism, creating a pathway for remote attackers to exploit the system. The vulnerability specifically targets the way Extbase processes user-supplied parameters during action execution, allowing malicious actors to manipulate the framework's behavior through crafted requests.
The technical implementation of this vulnerability involves improper handling of action parameters within the Extbase framework's invocation chain. When a user submits a request containing specially crafted parameters, the framework fails to properly validate or sanitize these inputs before processing them as part of an action execution. This creates a scenario where attackers can inject malicious code or manipulate the framework's internal operations to achieve unauthorized access. The flaw essentially allows for code injection or information disclosure attacks by exploiting the framework's parameter handling mechanisms. According to CWE standards, this vulnerability maps to CWE-79 which describes Cross-site Scripting (XSS) and CWE-94 which covers Improper Control of Generation of Code, both of which are relevant to the code execution aspects of this vulnerability.
The operational impact of CVE-2016-5091 is significant for organizations running affected TYPO3 versions, as it provides attackers with multiple attack vectors. Remote attackers can potentially execute arbitrary code on vulnerable systems, which could lead to complete system compromise and unauthorized access to sensitive data. The vulnerability also enables information disclosure attacks, allowing attackers to extract sensitive system information, user credentials, or database contents. Organizations using TYPO3 for content management, e-commerce platforms, or enterprise web applications are particularly at risk since these systems often contain valuable data and serve as critical business infrastructure. The attack surface extends beyond simple information disclosure to include full system compromise, making this vulnerability particularly dangerous from a security perspective.
Mitigation strategies for CVE-2016-5091 primarily focus on immediate version upgrades to patched releases of TYPO3. Organizations should prioritize upgrading to TYPO3 versions 6.2.24, 7.6.8, or 8.1.1 and later, depending on their current version. Additionally, implementing proper input validation at the application level can provide temporary protection while upgrades are being deployed. Security measures should include monitoring for suspicious parameter patterns and implementing web application firewalls that can detect and block malicious Extbase action requests. Organizations should also conduct thorough security assessments of their TYPO3 installations to identify any potential exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving command and control communication and privilege escalation, making it essential for security teams to monitor network traffic for anomalous patterns and implement proper access controls. Regular security updates and patch management processes should be reinforced to prevent similar vulnerabilities from occurring in the future, as this flaw demonstrates the importance of proper input validation in web application frameworks.