CVE-2026-100549 in OpenClaw
Summary
by MITRE • 09/26/2026
OpenClaw versions before 2026.8.1 contain a path traversal vulnerability in QQBot voice attachment handling where filenames are decoded twice, allowing encoded traversal segments to reappear after sanitization. Attackers can supply crafted voice attachments that write files outside the intended staging directory to other process-writable locations.
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Analysis
by VulDB Data Team • 09/26/2026
The identified security flaw resides within the OpenClaw software suite prior to version 2026.8.1, specifically affecting the component responsible for processing QQBot voice attachments. This vulnerability is classified as a path traversal issue that stems from an improper handling of input data during file name sanitization processes. The core technical deficiency involves the application performing double decoding on user-supplied filenames associated with uploaded voice files. In standard secure coding practices, input validation and sanitization should occur after all encoding transformations have been resolved to ensure that malicious payloads are neutralized before being processed by the operating system or underlying storage mechanisms. However, in this implementation, the filename undergoes an initial decoding phase followed by a secondary decoding step only during specific processing stages rather than at the point of ingestion. This architectural oversight allows attackers to craft filenames containing encoded path traversal sequences such as percent-encoded dots and slashes that remain inert during the first pass but are interpreted as literal directory navigation characters after the second decode operation occurs later in the pipeline.
This double-decoding mechanism effectively bypasses any preliminary sanitization checks designed to block absolute paths or relative traversals like dot-dot-slash sequences. When an attacker submits a maliciously crafted voice attachment with such an encoded filename, the system initially accepts it as valid because the traversal characters are not yet visible in their decoded form. Subsequently, when the file is being saved to disk, the second decoding step reveals these hidden path segments. Consequently, instead of creating a new file within the designated staging directory for temporary voice processing, the application writes the output file to an arbitrary location on the filesystem determined by the attacker. This behavior violates the principle of least privilege and strict input validation, allowing unauthorized access to write operations in directories that may be writable by the process but are outside the intended sandboxed environment.
The operational impact of this vulnerability is significant as it enables remote code execution or system compromise depending on the context in which OpenClaw operates. If the application runs with elevated privileges or if an attacker can predict a path leading to a web-accessible directory, they may achieve arbitrary file write capabilities that could lead to further exploitation vectors such as web shell deployment or configuration tampering. Even without immediate code execution, this flaw allows for denial of service through disk space exhaustion in critical system directories or data integrity issues by overwriting legitimate files with malicious content. The ability to write outside the staging directory undermines the isolation boundaries established by the application architecture and exposes sensitive infrastructure components to potential manipulation.
From a classification perspective, this vulnerability aligns closely with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, which describes flaws where software does not properly neutralize special elements within file paths that can resolve to directories outside of the restricted location. Additionally, it relates to CWE-178: Incorrect Handling of Final Unicode Normalization Case due to the reliance on encoding transformations for security checks rather than canonical form validation. In terms of offensive tactics, this exploitation technique maps to MITRE ATT&CK Tactic TA0003 Persistence and TA0005 Defense Evasion, specifically leveraging techniques that allow adversaries to place files in unexpected locations to maintain access or evade detection by standard monitoring tools focused on expected directories.
Mitigation strategies must prioritize immediate patching of the OpenClaw software to version 2026.8.1 or later where this double-decoding flaw has been addressed. In addition to updating, administrators should implement strict input validation that canonicalizes file paths before any processing occurs and ensures that all encoding is resolved prior to sanitization checks. It is also recommended to enforce a whitelist approach for allowed characters in filenames rather than relying solely on blacklist filters which can be bypassed through various encoding tricks. Furthermore, running the application with minimal necessary permissions using chroot jails or containerized environments can limit the blast radius of such vulnerabilities by restricting write access strictly to designated temporary directories regardless of path traversal attempts. Regular security audits focusing on file handling logic and automated static analysis tools configured to detect double-decoding patterns should be integrated into the development lifecycle to prevent similar issues in future releases.