CVE-2026-92919 in admin3
Summary
by MITRE • 09/17/2026
admin3 through 3.0.0 fails to sanitize client-supplied filenames in the upload handler, allowing authenticated users to write files outside the storage root on Windows deployments. Attackers can use dot-dot path segments in filenames to escape the configured storage directory and overwrite arbitrary files accessible to the server process.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified in admin3 versions through 3.0.0 represents a critical Path Traversal flaw within the application's file upload handler, specifically affecting Windows-based deployments. This security defect stems from an insufficient sanitization of client-supplied filenames during the file ingestion process. When users authenticate and attempt to upload files, the backend system fails to adequately validate or normalize the provided filename string before using it in filesystem operations. Consequently, if a malicious actor includes relative path traversal sequences, such as dot-dot segments (..), within the filename metadata, the application interprets these literally rather than stripping them out. This oversight allows the attacker to manipulate the intended destination directory of the uploaded file, effectively breaking out of the designated storage root and writing data into arbitrary locations on the server's filesystem that are accessible by the process running with elevated privileges or specific service account permissions.
From a technical perspective, this flaw aligns directly with Common Weakness Enumeration (CWE) ID 22: Improper Limitation of a Pathname to a Restricted Directory. The core issue lies in the lack of robust input validation and path canonicalization before file system access is granted. In Windows environments, where case insensitivity and specific directory separator handling can sometimes complicate security controls, this vulnerability becomes particularly exploitable if the application does not strictly enforce absolute paths or normalize inputs against a predefined whitelist of allowed characters and structures. The absence of these safeguards means that an authenticated user can bypass intended isolation boundaries, turning what should be a simple file storage feature into a mechanism for arbitrary file write operations.
The operational impact of this vulnerability is severe due to the potential for remote code execution and system compromise. By overwriting critical configuration files, script libraries, or executable binaries located outside the web root but within reach of the server process, an attacker can inject malicious payloads that are subsequently executed by the application logic. For instance, if the vulnerable service runs under a context with write access to system directories or application-specific folders containing startup scripts, the attacker could replace legitimate files with trojanized versions. This leads to unauthorized code execution, data integrity loss, and potentially full control over the underlying operating system. Furthermore, because authentication is required, this vulnerability typically falls under privilege escalation scenarios where a lower-privileged user leverages misconfigured permissions or logic flaws to achieve higher-level access.
In terms of threat modeling and adversary behavior, this exploitation technique corresponds to ATT&CK tactic T1059: Command and Scripting Interpreter, specifically through the sub-technique of file manipulation for persistence or execution setup. It also relates to TA0004: Privilege Escalation if the overwritten files grant access to more sensitive areas of the system. The ability to write arbitrary files is a foundational step in many attack chains, often serving as the initial foothold that enables subsequent lateral movement or data exfiltration depending on what resources are accessible from the newly written file locations.
To mitigate this vulnerability, immediate remediation should focus on implementing strict input validation and secure path handling mechanisms within the upload handler code. Developers must ensure that all filenames are normalized using standard library functions that resolve relative paths to their absolute equivalents before any filesystem interaction occurs. Additionally, a whitelist approach for allowed filename characters is recommended to reject inputs containing traversal sequences or other suspicious patterns outright rather than attempting to sanitize them post-facto. Implementing chroot jails or sandboxed environments with restricted write permissions can also limit the blast radius of such an exploit by ensuring that even if path traversal succeeds, the attacker cannot access sensitive system files outside their designated scope. Regular security audits and static code analysis tools configured to detect CWE-22 patterns are essential for preventing similar issues in future development cycles.