An arbitrary file write vulnerability (CWE-73, External Control of File Name or Path) exists in the consciousness-explorer component of sublinear-time-solver. The MCP export state (and import state) tool accepted a user-supplied filepath argument and passed it directly to fs.writeFileSync / fs.readFileSync without constraining the destination or rejecting path traversal. An attacker able to invoke the MCP tool could write or overwrite any file accessible to the server process (e.g. ~/.ssh/authorized keys, application files), leading to integrity loss and potential service disruption.

The same sink class was present in the main solver MCP server (saveVectorToFile / loadVectorFromFile).

State/vector files are now confined to a dedicated directory (overridable via $CONSCIOUSNESS EXPLORER STATE DIR / $SUBLINEAR SOLVER VECTOR DIR), a basename-only contract is enforced (rejecting separators, .., NUL/control chars, hidden files, and Windows reserved names), and files are opened with O NOFOLLOW | O CLOEXEC mode 0o600. Covered by 14 regression tests in tests/consciousness/safe-path.test.mjs.

Breaking change: callers must now pass a basename, not an absolute path.

Do not expose the MCP server to untrusted clients; restrict export state to trusted local users; run the server under a low-privilege account with a restricted working directory.