{"id":"PYSEC-2026-3592","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: `\u003c 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.","aliases":["CVE-2026-59216","GHSA-74h3-cxq7-vc5q"],"modified":"2026-08-04T14:30:29.928000066Z","published":"2026-08-04T11:34:42.837663Z","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"},{"type":"PACKAGE","url":"https://pypi.org/project/open-webui"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-74h3-cxq7-vc5q"}],"affected":[{"package":{"name":"open-webui","ecosystem":"PyPI","purl":"pkg:pypi/open-webui"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.10.0"}]}],"versions":["0.1.124","0.1.125","0.2.0","0.2.1","0.2.2","0.2.3","0.2.4","0.2.5","0.3.0","0.3.1","0.3.10","0.3.12","0.3.13","0.3.14","0.3.15","0.3.16","0.3.17","0.3.17.dev2","0.3.17.dev3","0.3.17.dev4","0.3.17.dev5","0.3.18","0.3.19","0.3.2","0.3.20","0.3.21","0.3.22","0.3.23","0.3.24","0.3.25","0.3.26","0.3.27","0.3.27.dev1","0.3.27.dev2","0.3.27.dev3","0.3.28","0.3.29","0.3.3","0.3.30","0.3.30.dev1","0.3.30.dev2","0.3.31","0.3.31.dev1","0.3.32","0.3.33","0.3.33.dev1","0.3.34","0.3.35","0.3.4","0.3.5","0.3.6","0.3.7","0.3.8","0.3.9","0.4.0","0.4.0.dev1","0.4.0.dev2","0.4.1","0.4.2","0.4.3","0.4.4","0.4.5","0.4.6","0.4.6.dev1","0.4.7","0.4.8","0.5.0","0.5.0.dev1","0.5.0.dev2","0.5.1","0.5.10","0.5.11","0.5.12","0.5.13","0.5.14","0.5.15","0.5.16","0.5.17","0.5.18","0.5.19","0.5.2","0.5.20","0.5.3","0.5.3.dev1","0.5.4","0.5.5","0.5.6","0.5.7","0.5.8","0.5.9","0.6.0","0.6.1","0.6.10","0.6.11","0.6.12","0.6.13","0.6.14","0.6.15","0.6.16","0.6.18","0.6.19","0.6.2","0.6.20","0.6.21","0.6.22","0.6.23","0.6.24","0.6.25","0.6.26","0.6.26.dev1","0.6.27","0.6.28","0.6.29","0.6.3","0.6.30","0.6.31","0.6.32","0.6.33","0.6.34","0.6.35","0.6.36","0.6.37","0.6.38","0.6.39","0.6.4","0.6.40","0.6.41","0.6.42","0.6.43","0.6.5","0.6.6","0.6.6.dev1","0.6.7","0.6.8","0.6.9","0.7.0","0.7.1","0.7.2","0.8.0","0.8.1","0.8.10","0.8.11","0.8.12","0.8.2","0.8.3","0.8.4","0.8.5","0.8.6","0.8.7","0.8.8","0.8.9","0.9.0","0.9.1","0.9.2","0.9.3","0.9.4","0.9.5","0.9.6"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/open-webui/PYSEC-2026-3592.yaml"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N"}]}