CVE-2026-113651 in ApostropheCMS
Summary
by MITRE • 10/20/2026
ApostropheCMS is an open-source Node.js content management system, and uploadfs is its file storage library. Prior to uploadfs 1.28.0, attacker-controlled paths that reach the local backend can contain parent-directory segments that escape the configured upload directory and affect file reads, writes, and deletion on the host filesystem. Exploitability depends on an application exposing the relevant uploadfs operations to untrusted path. This issue is fixed in uploadfs 1.28.0.
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Analysis
by VulDB Data Team • 10/20/2026
ApostropheCMS relies on the uploadfs library for managing file storage operations, a critical component that handles how content assets are persisted and retrieved within the application environment. The vulnerability identified prior to version 1.28.0 stems from an insufficient validation of user-supplied path segments when interacting with the local backend storage system. Specifically, the software failed to adequately sanitize or normalize paths containing parent-directory traversal sequences, commonly known as dot-dot-slash patterns such as ..../ This flaw allows an attacker who can control the file path input for uploadfs operations to bypass the intended directory confinement restrictions configured by the administrator.
The technical core of this vulnerability is a classic Path Traversal issue where the application does not strictly enforce that all file access requests remain within the designated safe root directory. When an untrusted user provides a path containing these escape sequences, the underlying filesystem operations interpret them as instructions to move up one or more levels in the directory hierarchy. Consequently, instead of writing or reading files exclusively within the upload folder, the system may resolve paths that point outside this boundary. This behavior violates the principle of least privilege and proper isolation boundaries expected from a secure content management system backend.
The operational impact of this flaw is severe because it directly compromises the integrity and availability of the host filesystem where ApostropheCMS is deployed. An authenticated attacker with access to file upload or manipulation features can exploit this weakness to overwrite critical application files, inject malicious scripts into publicly accessible directories for web shell deployment, or delete essential system data. In worst-case scenarios, if the server process runs with elevated privileges, an attacker could potentially read sensitive configuration files containing database credentials or other secrets located in parent directories, leading to a complete compromise of the underlying infrastructure and potential lateral movement within the network.
This vulnerability aligns with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, which describes flaws where software does not properly restrict paths to valid external resources. From an offensive security perspective, this behavior is consistent with ATT&CK technique T1083: File and Directory Discovery, as it enables unauthorized access to arbitrary files on the system for reconnaissance or further exploitation. The exploitability of this issue is contingent upon the specific application configuration exposing uploadfs endpoints to untrusted users without adequate authentication or authorization controls, but when such exposure exists, the risk is immediate and high severity due to the direct impact on file system integrity.
To mitigate this vulnerability, organizations running ApostropheCMS must ensure they are using version 1.28.0 of the uploadfs library or later, where the path validation logic has been corrected to properly reject or normalize dangerous traversal sequences before filesystem interaction is attempted. Administrators should also implement defense-in-depth strategies by configuring web servers and application firewalls to block requests containing dot-dot-slash patterns at the network perimeter. Additionally, running the CMS process with restricted file system permissions can limit the blast radius of any successful exploitation attempt, ensuring that even if path traversal occurs, the attacker cannot access sensitive areas outside the designated upload directory or critical system paths.