CVE-2026-103648 in image-downloader
Summary
by MITRE • 10/02/2026
Path traversal in image-downloader 4.3.0 allows an attacker who can control the download URL to cause downloaded response data to be written outside the configured destination directory.
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Analysis
by VulDB Data Team • 10/02/2026
The vulnerability identified as a path traversal flaw within version 4.3.0 of the image-downloader software represents a critical security deficiency in how input validation and file system operations are handled during resource retrieval processes. This specific weakness allows an attacker who possesses the ability to control or influence the download URL parameter to manipulate the underlying file paths used by the application. By injecting maliciously crafted sequences into the target URI, such as directory traversal characters like dot-dot-slash combinations, the attacker can bypass intended access controls and direct the software to write downloaded response data outside of the designated destination directory. This behavior indicates a failure in sanitizing user-supplied input before it is processed by file system APIs, which is a classic example of improper restriction of path canonicalization errors where the application does not adequately verify that the resolved absolute path remains within an expected base directory.
From a technical perspective, this flaw stems from insufficient validation logic when constructing local file paths based on external inputs. When the image-downloader component receives a URL to fetch content, it likely extracts filename components or constructs target paths without properly normalizing them against the configured root directory. If the application simply appends user-controlled segments to a base path without checking for parent directory references, an attacker can navigate up the file system hierarchy using standard traversal sequences. This allows the writing of arbitrary files to sensitive locations on the server's operating system, potentially overwriting existing configuration files, injecting malicious scripts into web-accessible directories, or placing executable payloads in temporary storage areas that may be executed by other services. The core issue lies in the lack of robust path canonicalization and boundary checking mechanisms before performing write operations.
The operational impact of this vulnerability is severe, as it can lead to a wide range of adverse outcomes depending on the context in which the image-downloader service operates. If an attacker successfully writes files outside the intended directory, they may achieve remote code execution if the written file is subsequently executed by another process or served directly via a web server with appropriate permissions. Even without direct code execution, the ability to write arbitrary files can facilitate further attacks such as defacement of public-facing websites through overwriting index pages, poisoning cache mechanisms, or disrupting service availability by filling up disk space in critical system directories. In environments where multiple tenants share storage resources, this vulnerability could also lead to data leakage if sensitive information from other users is overwritten or accessed via the manipulated paths.
To mitigate this risk, developers must implement strict input validation and path normalization techniques within the image-downloader component. All user-supplied URLs should be parsed carefully, and any extracted filename components must be validated against a whitelist of allowed characters while ensuring that no directory traversal sequences are present. It is essential to resolve the full absolute path of both the intended destination and the base directory before comparison, using standard library functions designed for canonicalizing paths rather than relying on string manipulation alone. Additionally, employing chroot jails or containerization strategies can limit the blast radius by restricting file system access to specific directories regardless of traversal attempts. Regular security audits focusing on file handling operations and adherence to industry standards such as CWE-22 which covers Improper Limitation of a Pathname to a Restricted Directory are recommended to prevent similar vulnerabilities in future iterations of the software.