What happened
NVD published CVE-2026-66004 (CVSS 6.0, Medium) on 2026-07-24, describing a path traversal vulnerability in BlenderMCP's asset-download tool triggered by unsanitized traversal sequences in a third-party API response.
Why it matters
This is a concrete example of an MCP tool trusting external API response data without sanitization — an attack surface unique to agentic tool-calling architectures, where an LLM agent invoking the tool can be steered via prompt injection or a MITM'd upstream response to write attacker-controlled files onto the host filesystem.
Attack vector
The download_polyhaven_asset method fails to sanitize traversal sequences in API response 'include' keys, allowing attackers who control the API response (via MITM) or who can inject malicious content into an LLM agent's context (prompt injection) to cause arbitrary file writes outside the intended asset directory.
Affected systems
BlenderMCP before commit 30a3308
Mitigation
Upgrade to the fixed commit 30a3308446cd8f81a9446e5a2ed657c0d8d86072.