CVE-2014-7226 in HTTP File Server
Summary
by MITRE
The file comment feature in Rejetto HTTP File Server (hfs) 2.3c and earlier allows remote attackers to execute arbitrary code by uploading a file with certain invalid UTF-8 byte sequences that are interpreted as executable macro symbols.
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Analysis
by VulDB Data Team • 08/17/2025
The vulnerability identified as CVE-2014-7226 resides within Rejetto HTTP File Server version 2.3c and earlier, representing a critical remote code execution flaw that exploits the file comment feature. This vulnerability specifically targets the server's handling of UTF-8 byte sequences during file comment processing, creating a pathway for malicious actors to execute arbitrary code on the affected system. The flaw demonstrates the dangerous intersection of character encoding interpretation and file processing capabilities within web servers, where seemingly benign input can be transformed into malicious payloads.
The technical mechanism behind this vulnerability involves the server's improper handling of invalid UTF-8 byte sequences within file comments. When users upload files with specific invalid UTF-8 sequences, the HTTP File Server interprets these sequences as executable macro symbols rather than plain text characters. This misinterpretation occurs during the comment processing phase where the server attempts to normalize or validate UTF-8 input. The vulnerability is classified as a buffer overflow or injection flaw that leverages the server's encoding handling routines, allowing attackers to inject executable code that gets processed and executed by the web server. This behavior aligns with CWE-170, which addresses improper handling of Unicode encoding, and represents a classic case of input validation failure in text processing components.
The operational impact of this vulnerability is severe and far-reaching for any organization utilizing affected versions of Rejetto HTTP File Server. Remote attackers can leverage this flaw to gain complete control over the affected server, potentially leading to data breaches, system compromise, and unauthorized access to sensitive information stored on the server. The vulnerability is particularly dangerous because it requires minimal privileges to exploit and can be executed remotely without authentication. Once successful, attackers can execute commands with the privileges of the web server process, potentially escalating to system-level access depending on the server configuration and user permissions. This vulnerability directly maps to ATT&CK technique T1059, which covers command and script injection, and T1078, which addresses valid accounts, as attackers can leverage compromised server processes to maintain persistent access.
Mitigation strategies for CVE-2014-7226 must address both immediate remediation and long-term security improvements. The primary recommendation involves upgrading to a patched version of Rejetto HTTP File Server, as the vendor has released updates that properly handle UTF-8 byte sequences and prevent the interpretation of invalid sequences as executable code. Organizations should also implement network-level restrictions to limit access to the affected server, particularly disabling unnecessary file upload capabilities and restricting file comment functionality. Input validation should be strengthened at multiple layers including web server configuration, application-level filtering, and network monitoring to detect and prevent malformed UTF-8 sequences from reaching the vulnerable processing components. Additionally, security teams should conduct comprehensive vulnerability assessments to identify any other systems running unpatched versions of the HTTP File Server and implement proper network segmentation to limit the potential blast radius of successful exploitation attempts.