CVE-2026-59216: Open WebUI Cross-user Code-interpreter And Tool Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-74h3-cxq7-vc5q",
  "modified" : "2026-07-24T17:01:53Z",
  "published" : "2026-07-24T17:01:53Z",
  "aliases" : [ "CVE-2026-59216" ],
  "summary" : "Open WebUI: Cross-user code-interpreter and tool execution via unvalidated Socket.IO event-caller session_id",
  "details" : "## Summary\n\nAn authenticated low-privilege user can execute arbitrary code-interpreter Python and tools inside **another** user's authenticated session. The Socket.IO event-caller (`get_event_call`) delivers `execute:python` / `execute:tool` events to a **client-supplied** `session_id` after only checking that the session is connected, never that it belongs to the requester. Combined with `ydoc:document:join`, which exposes the live socket ids of everyone in a shared note's collaboration room to any read-access participant, an attacker can target a victim's session and run attacker-chosen code/tools in the victim's browser context. When the victim is an administrator, that hijacked context reaches the admin-only Functions API, whose source is executed server-side, yielding remote code execution as the server process (root in the default container).\n\n## Affected component\n\n- `backend/open_webui/socket/main.py` — `get_event_call()` / `__event_caller__`\n- `backend/open_webui/main.py` — chat-completion metadata (`session_id` taken from the request body)\n\n## Root cause\n\nThe event-caller routes to a caller-controlled session id with no ownership check:\n\n```python\n# backend/open_webui/socket/main.py — get_event_call()\nasync def __event_caller__(event_data):\n    session_id = request_info['session_id']\n    if session_id not in SESSION_POOL:                 # only checks the session is connected\n        return {'error': 'Client session disconnected.'}\n    return await sio.call('events', {...}, to=session_id, ...)   # delivered to that sid\n```\n\n`session_id` originates from the request body and is never validated against the authenticated user:\n\n```python\n# backend/open_webui/main.py\nmetadata = {\n    'user_id': user.id,                               # server-derived (trustworthy)\n    'session_id': form_data.pop('session_id', None),  # client-controlled\n    ...\n}\n```\n\n`SESSION_POOL[session_id]` is the user record of whoever owns that socket. Because the caller checks only membership (`in SESSION_POOL`), a request carrying another user's `session_id` causes `execute:python` / `execute:tool` to be delivered to that other user's browser.\n\n## Reachability\n\n- `execute:python` / `execute:tool` are emitted from the code-interpreter and tool-call paths (`utils/middleware.py`, `tools/builtin.py`), all routed through `get_event_call`.\n- The victim's live `session_id` is disclosed to any read-access participant of a shared note via `ydoc:document:join`.\n- `POST /api/v1/chat/completions` requires only `get_verified_user` (the default user role). The attacker uses their own account and a model / Direct Connection they control to choose the payload.\n\n## Impact\n\n- **Any victim:** arbitrary code-interpreter Python and tool execution in the victim's authenticated session — the attacker acts with the victim's identity and origin (full session/account compromise).\n- **Admin victim:** the hijacked admin context reaches `POST /api/v1/functions/create`, whose source is `exec()`'d server-side → remote code execution as the server process (root in the default container).\n\nThe Functions API is intended administrator code-execution; the vulnerability here is the cross-user delivery that lets an attacker drive another user's session — including an admin's — into it. The primitive is a full session compromise even against non-admin victims.\n\n## Proof of Concept\n\nThe reporter's `exploit.py` reproduced on `ghcr.io/open-webui/open-webui:0.9.6` and a build of the `v0.9.6` tag, confirming blind server-side RCE out-of-band (callback returns `uid=0(root)`), using only a low-privilege `user` account that shared a note with an admin victim. Preconditions: code interpreter enabled; attacker shares a note with the victim; victim opens it while online; admin victim required for server RCE.\n\n## Fix\n\n`get_event_call` must verify the target session belongs to the requesting user before delivering, not merely that it is connected:\n\n```python\nsession = SESSION_POOL.get(session_id)\nif session is None or session.get('id') != request_info.get('user_id'):\n    return {'error': 'Client session disconnected.'}\n```\n\n`user_id` in the request metadata is server-derived from the authenticated user, so it is trustworthy. Restricting `ydoc:document:join` so it does not disclose other participants' socket ids is recommended as defence-in-depth.\n\n## Affected / Patched\n\n- Affected: `< 0.10.0` (last affected release 0.9.6)\n- Patched: v0.10.0. `get_event_call` now verifies the target session belongs to the requesting user before delivering (`session is None or session.get('id') != request_info.get('user_id')`), using the server-derived `user_id` from the request metadata. The recommended `ydoc:document:join` sid-disclosure restriction is defence-in-depth and independent of this fix; the ownership check closes the cross-user delivery regardless of whether the victim's sid is known.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "open-webui"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.10.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/security/advisories/GHSA-74h3-cxq7-vc5q"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59216"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/pull/25763"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/commit/386ac958144dbbbf0aa6e268070d72b681a318aa"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/open-webui/open-webui"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/releases/tag/v0.10.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-639", "CWE-862", "CWE-94" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-24T17:01:53Z",
    "nvd_published_at" : "2026-07-09T17:17:02Z"
  }
}