GHSA-7w82-6f9j-v9jp - mcp-sanitizer: File Path Sanitizer Permits Arbitrary User-Home Absolute Paths

## File Path Sanitizer Permits Arbitrary User-Home Absolute Paths ### Summary `mcp-sanitizer` v1.3.3 explicitly whitelists `/home/` and `/Users/` as allowed absolute path prefixes in its file path validation logic (`src/utils/validation-utils.js:188-196`). As a result, paths such as `/home/alice/.ssh/id_rsa` and `/home/alice/.aws/credentials` pass through `sanitizer.sanitize()` with `blocked=false`, even though they point to highly sensitive files outside any configured safe root. Any consumer application that trusts the sanitized path and passes it to a filesystem read/write operation (e.g., `fs.readFile`) will expose arbitrary user-home directory files to an unauthenticated network attacker. Dynamic reproduction confirmed exfiltration of a simulated SSH private key and AWS credentials via a single HTTP POST request. ### Details The vulnerability resides in the `validateFilePath` function inside `src/utils/validation-utils.js`. When an absolute path falls outside the configured safe root directories, the function performs a secondary check against a hardcoded allowlist: ```js // src/utils/validation-utils.js:188-196 if (!isInSafeLocation && path.isAbsolute(normalizedPath)) { const allowedAbsolutePaths = ['/tmp/', '/var/tmp/', '/home/', '/Users/']; const isAllowedAbsolute = allowedAbsolutePaths.some(allowed => normalizedPath.toLowerCase().startsWith(allowed.toLowerCase()) ); if (!isAllowedAbsolute) { throw new Error('Absolute path not in allowed safe directory'); } } ``` Because `/home/` and `/Users/` are included in `allowedAbsolutePaths`, any path beneath those directories — including `~/.ssh/id_rsa`, `~/.aws/credentials`, `~/.kube/config`, `~/.gnupg/`, etc. — is considered safe and passes validation unchanged. The dangerous paths (`dangerousUnixPaths` at `src/utils/validation-utils.js:135`) only cover `/etc/`, `/proc/`, `/sys/`, `/dev/`, `/root/`, `/boot/`, `/usr/bin/`, and `/sbin/`. Home-directory sensitive subdirectories (`.ssh`, `.aws