CVE-2026-35570

Description

A logic flaw exists in `bashToolHasPermission()` inside `src/tools/BashTool/bashPermissions.ts`. When the sandbox auto-allow feature is active and no explicit deny rule is configured, the function returns an `allow` result immediately — before the path constraint filter (`checkPathConstraints`) is ever evaluated. This allows commands containing path traversal sequences (e.g., `../../../../../etc/passwd`) to bypass directory restrictions entirely. ## Affected Component - **File:** `src/tools/BashTool/bashPermissions.ts` - **Function:** `bashToolHasPermission` - **Location:** ~line 1445 (sandbox auto-allow block) ## Vulnerable Code Flow ``` bashToolHasPermission() │ ├─ [~1445] Sandbox auto-allow block │ └─ No deny rule found → return ALLOW ⚠️ Early exit │ └─ [~1644] checkPathConstraints() ❌ Never reached ``` The sandbox block was designed to skip interactive permission prompts in sandboxed environments. However, it unintentionally also skips the path traversal filter, which is a separate and critical security control. ## Impact Any process or user operating in a sandboxed session with no explicit deny rules can: - Read arbitrary files outside the sandbox boundary (e.g., `/etc/passwd`, `/etc/shadow`, `.env` files, SSH private keys) - Write to arbitrary paths (subject to OS-level permissions) - Fully defeat the filesystem isolation that the sandbox is intended to enforce ## Steps to Reproduce 1. Enable sandbox mode: `SandboxManager.isSandboxingEnabled() = true` 2. Enable auto-allow: `SandboxManager.isAutoAllowBashIfSandboxedEnabled() = true` 3. Ensure no explicit deny rules are configured for the session 4. Submit a bash command with a path traversal payload: ``` cat ../../../../../etc/passwd ``` 5. Observe that the command receives `behavior: allow` without triggering `checkPathConstraints` ## Recommended Fix The sandbox auto-allow block should **never short-circuit the full permission pipeline**. It may suppress interactive prompts, but path constraint validation must always execute. ### Option 1 — Preferred: Continue pipeline on `allow` Only return early for `deny` or `ask` behaviors. Let `allow` fall through to `checkPathConstraints`: ```typescript if ( SandboxManager.isSandboxingEnabled() && SandboxManager.isAutoAllowBashIfSandboxedEnabled() && shouldUseSandbox(input) ) { const sandboxAutoAllowResult = checkSandboxAutoAllow( input, appState.toolPermissionContext, ); if (sandboxAutoAllowResult.behavior !== 'allow') { // Only block or prompt — never skip path checks on allow return sandboxAutoAllowResult; } // If 'allow', continue to checkPathConstraints below } ``` ### Option 2 — Defense in depth: Run path check before returning Run `checkPathConstraints` explicitly inside the sandbox block before returning: ```typescript if (sandboxAutoAllowResult.behavior !== 'passthrough') { const pathCheck = checkPathConstraints(input, appState.toolPermissionContext); if (pathCheck.behavior !== 'allow') { return pathCheck; // Block traversal attempts even in sandbox } return sandboxAutoAllowResult; } ``` ### Option 3 — Minimal change: Move sandbox block after path check Reorder the function so `checkPathConstraints` always runs first, and the sandbox block only handles the prompt-suppression logic afterward. --- Credit: Elvin Latifli (@Rickidevs )