What happened
NVD published CVE-2026-18991 (CVSS 7.3, High) on August 6, 2026, describing a path-traversal flaw in the send_file component of NanoClaw's MCP tool set within its container-based agent runner.
Why it matters
Path traversal in an agent's file-handling MCP tool can let a manipulated LLM read or overwrite files outside its sandboxed working directory, risking host file disclosure or tampering from a single-author niche agent framework with a public exploit already disclosed.
Attack vector
The send_file MCP tool in the agent-runner container fails to sanitize file paths, allowing a remote attacker (via LLM tool-call manipulation) to traverse outside the intended directory and read/write arbitrary files on the host.
Affected systems
nanocoai NanoClaw ≤ 2.0.64
Mitigation
Update to a patched NanoClaw release; monitor github.com/nanocoai/nanoclaw for advisory.