That1Drifter browse-mcp up to 0.8.1 Download browser_download save_dir path traversal

Summaryinfo

A vulnerability was found in That1Drifter browse-mcp up to 0.8.1. It has been declared as critical. Affected by this vulnerability is the function browser_download of the component Download. The manipulation of the argument save_dir results in path traversal. This vulnerability is reported as CVE-2026-55557. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in That1Drifter browse-mcp up to 0.8.1. It has been classified as critical. Affected is the function browser_download of the component Download. The manipulation of the argument save_dir with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

browse-mcp is a Playwright-based headless-browser MCP server for MCP-capable agents. Prior to 0.8.2, browser_download writes a fetched response body to join(save_dir, filename) without validating the caller-controlled save_dir, while browser_save_state and browser_load_state honor a caller-controlled path unchanged. A malicious MCP client, or an autonomous agent steered by indirect prompt injection on a visited page, can choose an arbitrary save_dir or state path and a URL whose response body becomes attacker-controlled file contents, allowing writes to any path the process can reach, including ~/.bashrc, autostart entries, or cron files, and potentially leading to host code execution. The force_fetch fallback also uses a raw fetch() that bypasses the BROWSE_MCP_ALLOWED_ORIGINS origin fence. This issue is fixed in version 0.8.2.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-55557 since 06/17/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1006 by the MITRE ATT&CK project.

Upgrading to version 0.8.2 eliminates this vulnerability.

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Productinfo

Type

• Artificial Intelligence Software

Vendor

• That1Drifter

Name

• browse-mcp

Version

• 0.8.0
• 0.8.1

Website

• Product: https://github.com/That1Drifter/browse-mcp/

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CPE 2.2info

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