CVE-2010-5099 in TYPO3
Summary
by MITRE
The fileDenyPattern functionality in the PHP file inclusion protection API in TYPO3 4.2.x before 4.2.16, 4.3.x before 4.3.9, and 4.4.x before 4.4.5 does not properly filter file types, which allows remote attackers to bypass intended access restrictions and access arbitrary PHP files, as demonstrated using path traversal sequences with %00 null bytes and CVE-2010-3714 to read the TYPO3 encryption key from localconf.php.
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Analysis
by VulDB Data Team • 12/02/2025
The vulnerability CVE-2010-5099 represents a critical flaw in TYPO3's file inclusion protection mechanism that fundamentally undermines the security of web applications built on this platform. This weakness exists within the fileDenyPattern functionality of TYPO3's PHP file inclusion protection API, which was designed to prevent unauthorized access to sensitive files through malicious path traversal attacks. The vulnerability affects multiple versions of TYPO3 including 4.2.x before 4.2.16, 4.3.x before 4.3.9, and 4.4.x before 4.4.5, indicating a widespread issue that impacted a significant portion of the TYPO3 user base during that time period. The flaw specifically manifests in the improper filtering of file types, creating a pathway for remote attackers to circumvent intended access controls and gain unauthorized access to arbitrary PHP files on the server.
The technical exploitation of this vulnerability leverages path traversal sequences combined with null byte injection techniques to bypass the intended file access restrictions. Attackers can utilize %00 null bytes in their malicious requests to terminate string processing and manipulate the file inclusion logic, effectively allowing them to traverse the file system beyond the intended boundaries. This technique directly relates to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal vulnerabilities. The vulnerability's exploitation is particularly dangerous because it allows attackers to read sensitive configuration files such as localconf.php, which contains the TYPO3 encryption key. This encryption key is crucial for the application's security as it's used for encrypting various sensitive data within the TYPO3 system, making the compromise of this key potentially devastating for the entire application's security posture.
The operational impact of CVE-2010-5099 extends far beyond simple unauthorized file access, as it provides attackers with the means to escalate their privileges and potentially gain full control over affected TYPO3 installations. The ability to read the encryption key from localconf.php compromises the confidentiality of encrypted data stored within the application, including user credentials, session data, and other sensitive information. This vulnerability also enables attackers to execute arbitrary PHP code on the server, as they can access and include PHP files that contain malicious code. The attack vector aligns with ATT&CK technique T1566, which describes the use of malicious file inclusion to execute code, and T1078, which covers valid accounts and legitimate credentials for persistence. Organizations running affected TYPO3 versions were particularly vulnerable because the flaw allowed attackers to bypass the security controls that should have prevented them from accessing system configuration files, which are typically protected from direct web access.
The mitigation strategy for CVE-2010-5099 requires immediate patching of all affected TYPO3 installations to versions 4.2.16, 4.3.9, and 4.4.5 respectively, which contain the necessary fixes to properly implement file type filtering and prevent the bypass of access restrictions. Additionally, organizations should implement proper input validation and sanitization measures to prevent null byte injection attacks, and ensure that sensitive configuration files are not accessible through web directories. Network segmentation and access control measures should be strengthened to limit exposure of TYPO3 installations to untrusted networks. Security monitoring should include detection of path traversal attempts and null byte injection patterns in web application logs. The vulnerability serves as a critical reminder of the importance of proper input validation and the potential consequences of inadequate file access controls in web applications, particularly those that handle sensitive data and encryption keys. Organizations should conduct thorough security assessments of their web applications to identify similar vulnerabilities and implement comprehensive security measures that address both the immediate threat and potential future exploits of this nature.