Path Traversal in Picobot Workspace Handler

Executive Summary

CVE-2026-15629 is a vulnerability in louisho5 picobot versions up to 0.2.0. It affects the CreateSkill/GetSkill function in the file internal/agent/tools/filesystem.go within the Workspace Handler component.

The vulnerability involves improper link resolution, specifically hardlink aliases. An attacker can manipulate the system to bypass workspace boundaries by creating a hardlink inside the workspace that points to an external file. This allows the attacker to read or overwrite files outside the intended workspace using the filesystem or skill tools.

The issue arises because the filesystem and skill tools do not properly validate file access or modifications to ensure they remain within the workspace. The default agent loop also registers an unconstrained 'exec' tool, which enables the creation of hardlinks, making the attack feasible.

This vulnerability is classified under CWE-59 (Improper Link Resolution Before File Access) and has been publicly disclosed, increasing the risk of exploitation.

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Detection Guidance

Detecting this vulnerability involves checking for signs of hardlink exploitation within the Picobot workspace or identifying unauthorized file access outside the intended workspace boundaries.

• Inspect the Picobot workspace directory for hardlinks pointing to files outside the workspace. On Linux systems, you can use the `ls -i` command to list inode numbers and `find` to locate hardlinks. For example: `find /path/to/workspace -type f -links +1 -exec ls -i {} \;`
• Check for unexpected file modifications or access to sensitive files outside the workspace. Use commands like `lsof` to monitor open files by the Picobot process: `lsof -p $(pgrep picobot)`
• Review Picobot logs for unusual filesystem operations or skill executions, particularly those involving the `exec` tool or filesystem-related actions.
• Verify the version of Picobot running on your system. If it is version 0.2.0 or earlier, it is vulnerable. You can check the version by running the binary with the `--version` flag or inspecting the configuration file.

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Impact Analysis

This vulnerability can impact you in several ways if you are using louisho5 picobot up to version 0.2.0:

• Confidentiality compromise: An attacker with access to the Picobot process can read sensitive files outside the intended workspace by exploiting hardlinks.
• Integrity compromise: An attacker can overwrite or modify files outside the workspace, potentially altering critical system or application files.
• Privilege escalation: If the Picobot process runs with elevated privileges, the attacker may gain access to files or system areas they would not normally have permission to interact with.
• Remote exploitation: The vulnerability can be exploited remotely, increasing the risk of unauthorized access to your system.

The CVSS v3.1 score of 6.3 (Medium severity) indicates that the vulnerability poses a significant risk, particularly if sensitive data or system files are accessible to the Picobot process.

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Compliance Impact

This vulnerability can affect compliance with common standards and regulations in the following ways:

• GDPR (General Data Protection Regulation): If Picobot processes or has access to personal data of EU citizens, the vulnerability could lead to unauthorized access or disclosure of this data. GDPR requires strict controls over personal data, and a breach could result in non-compliance, fines, or legal action.
• HIPAA (Health Insurance Portability and Accountability Act): If Picobot is used in a healthcare environment and has access to protected health information (PHI), the vulnerability could compromise the confidentiality and integrity of PHI. HIPAA mandates safeguards to protect PHI, and a breach could lead to violations and penalties.
• Other standards (e.g., ISO 27001, NIST): Many compliance frameworks require organizations to implement controls to prevent unauthorized access to sensitive data. This vulnerability undermines such controls, potentially leading to non-compliance with requirements related to access control, data integrity, and risk management.

Organizations using Picobot in regulated environments should assess the risk posed by this vulnerability and take corrective actions to maintain compliance.

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Mitigation Strategies

To mitigate this vulnerability, follow these immediate steps to reduce the risk of exploitation.

• Upgrade Picobot to the latest version if a patch is available. Monitor the project's GitHub repository for updates or security fixes.
• Restrict the use of the `exec` tool in the Picobot configuration to prevent hardlink creation. Remove or disable the `exec` tool from the agent loop if it is not required for your use case.
• Limit the permissions of the Picobot process account to minimize the impact of potential exploitation. Run Picobot with the least privileges necessary, avoiding root or administrative access.
• Monitor the workspace directory for unauthorized hardlinks or file modifications. Implement file integrity monitoring tools to detect and alert on suspicious changes.
• Isolate the Picobot instance from sensitive files and directories. Use containerization or sandboxing techniques to restrict access to the host filesystem.
• Review and audit the skills and tools registered in the Picobot configuration. Remove any unnecessary or high-risk tools that could be leveraged for exploitation.

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