CVE-2026-86542 in Knowns
Summary
by MITRE • 09/08/2026
knowns before 0.30.0 fails to validate import names in the import routes, allowing unauthenticated attackers to write files outside the imports directory. Attackers can supply traversal sequences in the name parameter to escape the imports directory and overwrite arbitrary files writable by the server process.
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Analysis
by VulDB Data Team • 09/08/2026
The vulnerability identified in versions of the software prior to 0.30.0 stems from a critical failure in input validation within the import routing mechanism. Specifically, the application does not adequately sanitize or validate user-supplied filenames provided via the name parameter during file import operations. This lack of rigorous path normalization allows attackers to manipulate the intended directory structure by injecting directory traversal sequences, commonly known as dot-dot-slash patterns such as ../ into the input field. In a secure implementation, any attempt to reference directories above the designated imports folder should be intercepted and rejected or normalized to remain within the allowed scope. However, due to this oversight, the underlying file system operations interpret these sequences literally, causing the application to write data outside of its intended sandboxed directory.
This flaw constitutes an Arbitrary File Write vulnerability, which is categorized under CWE-434 in the Common Weakness Enumeration standards. The operational impact of this issue is severe because it grants unauthenticated attackers the ability to overwrite arbitrary files on the server's file system, provided those files are writable by the user account running the application process. By exploiting this weakness, an attacker can potentially replace critical configuration files, inject malicious scripts into web-accessible directories, or corrupt essential application data. This level of control over the file system often serves as a precursor to more devastating attacks, including Remote Code Execution (RCE), where the attacker leverages the written content to execute arbitrary commands on the host machine with the privileges of the compromised service account.
From an offensive security perspective, this vulnerability aligns with techniques observed in the MITRE ATT&CK framework, particularly those related to File and Directory Manipulation under the Persistence or Impact tactics. An adversary might use this flaw to plant backdoors, modify system configurations to maintain access, or disrupt availability by corrupting key files. The absence of authentication requirements for this specific endpoint exacerbates the risk, as it allows any external actor on the network to attempt exploitation without needing valid credentials first. This significantly lowers the barrier to entry for attackers and increases the likelihood of successful compromise in environments where perimeter defenses are not strictly enforced at the application layer.
To mitigate this vulnerability, organizations must upgrade immediately to version 0.30.0 or later, which includes patches that enforce strict validation on import names. In addition to upgrading, developers should implement defense-in-depth strategies by ensuring all file paths are canonicalized before use and verifying that the resolved path remains within the expected base directory using allowlist approaches rather than relying solely on blacklist patterns for dangerous characters. Furthermore, applying principle of least privilege is essential; the application process should run with minimal permissions, restricting write access strictly to necessary directories and preventing writes to system-critical locations or web roots where executable code could be deployed. Regular security audits and static analysis tools configured to detect path traversal issues can also help identify similar weaknesses in other parts of the codebase before they are exploited in production environments.