CVE-2009-4790 in Multi Server
Summary
by MITRE
Multiple directory traversal vulnerabilities in Sysax Multi Server 4.5 allow remote authenticated users to read or modify arbitrary files via crafted FTP commands. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 11/17/2025
The vulnerability identified as CVE-2009-4790 represents a critical directory traversal flaw within Sysax Multi Server version 4.5, specifically affecting the File Transfer Protocol implementation. This vulnerability stems from inadequate input validation and sanitization mechanisms within the FTP server component, allowing authenticated remote attackers to manipulate file access paths through specially crafted FTP commands. The issue manifests when the server fails to properly sanitize user-supplied path information, enabling malicious actors to navigate outside the intended directory structures and access or modify arbitrary files on the underlying filesystem.
Directory traversal vulnerabilities of this nature fall under the Common Weakness Enumeration category CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory. The vulnerability operates by exploiting the absence of proper path validation controls that should prevent attackers from using sequences such as "../" or similar path manipulation techniques to escape the designated file access boundaries. This weakness enables attackers to bypass normal file access controls and potentially gain unauthorized access to sensitive system files, configuration data, or user information stored outside the intended server directories.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as authenticated users can leverage these flaws to modify critical system files, potentially leading to complete system compromise. Attackers could use the vulnerability to read sensitive configuration files, access user credentials stored in plain text, or even inject malicious code into system files. The authentication requirement adds a layer of complexity to exploitation, as attackers must first establish valid credentials, but once authenticated, they can perform actions that would normally be restricted to authorized users within the system's intended access controls.
From a cybersecurity perspective, this vulnerability aligns with tactics and techniques documented in the MITRE ATT&CK framework under the initial access and privilege escalation categories, specifically targeting the use of valid accounts for unauthorized file system access. The vulnerability represents a classic example of how insufficient input validation can create pathways for attackers to escalate their privileges and access resources beyond their intended scope. Organizations utilizing Sysax Multi Server 4.5 should immediately implement security patches or updates provided by the vendor, while also considering network segmentation and access control measures to limit the potential impact of such vulnerabilities. Additionally, implementing proper monitoring and logging of FTP access patterns can help detect anomalous file access behaviors that may indicate exploitation attempts.