PYSEC-2026-2735
Vulnerability from pysec - Published: 2026-07-13 15:15 - Updated: 2026-07-13 16:05Mass Assignment via Pydantic extra='allow' Allows Creating Folders in Other Users' Accounts
Affected Component
Folder creation endpoint and form model:
- backend/open_webui/models/folders.py (lines 72-77, FolderForm with extra='allow')
- backend/open_webui/models/folders.py (lines 95-106, insert_new_folder dict construction)
- backend/open_webui/routers/folders.py (line 119, create_folder endpoint)
Affected Versions
Current main branch (commit 6fdd19bf1) and likely all versions since FolderForm adopted extra='allow'.
Description
FolderForm uses model_config = ConfigDict(extra='allow'), which permits arbitrary fields to pass through Pydantic validation and be included in model_dump(exclude_unset=True). In insert_new_folder, the server-assigned user_id is placed at the start of the dict and then overwritten by the spread of form data:
# models/folders.py:95-106
folder = FolderModel(
**{
'id': id, # server
'user_id': user_id, # server — overwritten below
**(form_data.model_dump(exclude_unset=True) or {}), # user-controlled (extra='allow')
'parent_id': parent_id,
'created_at': int(time.time()),
'updated_at': int(time.time()),
}
)
Because FolderModel declares user_id: str as a real field (not just a form extra), any attacker-supplied user_id in the POST body is accepted by the model and persisted on the Folder row.
Attack Scenario
- Attacker discovers a victim's user ID. User UUIDs commonly leak via the user search endpoint (
GET /api/v1/users/search, intentionally accessible to verified users for sharing UI), shared chat metadata, or channel member lists. - Attacker sends:
POST /api/v1/folders/ { "name": "Important: Click here", "user_id": "<victim_user_id>", "meta": {"icon": "warning"}, "data": {...} } - Pydantic accepts the extra
user_idfield (allowed byextra='allow'). insert_new_folderspreads the form data over the server-set'user_id': user_id, overwriting it with the attacker's value.- The
Folderrow is persisted withuser_id = <victim_user_id>. - The victim sees the attacker-planted folder in their UI on next load because
GET /api/v1/folders/filters by the viewer's ownuser_id.
The attacker can repeat this to plant multiple folders, use crafted name values for phishing ("Click here to recover account" / "Security alert"), and abuse the meta and data fields to add visual elements that further mimic legitimate content.
Impact
- Unauthorized write into victim's folder tree
- Phishing surface: attacker-controlled
name,meta, anddatarender in the victim's UI in a trusted context - DoS / spam: attacker can flood a victim with arbitrary folders; victim must manually delete each one
- Attacker cannot read the folder back — all read paths filter by the caller's own
user_id— so confidentiality is preserved, but integrity and trust are compromised
Preconditions
- Attacker must have an authenticated account with
features.folderspermission (default for all users) - Attacker must know or guess the victim's user UUID (obtainable through various non-sensitive endpoints)
| Name | purl | open-webui | pkg:pypi/open-webui |
|---|
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "open-webui",
"purl": "pkg:pypi/open-webui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.9.0"
}
],
"type": "ECOSYSTEM"
}
],
"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"
]
}
],
"aliases": [
"CVE-2026-44550",
"GHSA-hr43-rjmr-7wmm"
],
"details": "# Mass Assignment via Pydantic extra=\u0027allow\u0027 Allows Creating Folders in Other Users\u0027 Accounts\n\n## Affected Component\n\nFolder creation endpoint and form model:\n- `backend/open_webui/models/folders.py` (lines 72-77, `FolderForm` with `extra=\u0027allow\u0027`)\n- `backend/open_webui/models/folders.py` (lines 95-106, `insert_new_folder` dict construction)\n- `backend/open_webui/routers/folders.py` (line 119, `create_folder` endpoint)\n\n## Affected Versions\n\nCurrent main branch (commit `6fdd19bf1`) and likely all versions since `FolderForm` adopted `extra=\u0027allow\u0027`.\n\n## Description\n\n`FolderForm` uses `model_config = ConfigDict(extra=\u0027allow\u0027)`, which permits arbitrary fields to pass through Pydantic validation and be included in `model_dump(exclude_unset=True)`. In `insert_new_folder`, the server-assigned `user_id` is placed at the start of the dict and then overwritten by the spread of form data:\n\n```python\n# models/folders.py:95-106\nfolder = FolderModel(\n **{\n \u0027id\u0027: id, # server\n \u0027user_id\u0027: user_id, # server \u2014 overwritten below\n **(form_data.model_dump(exclude_unset=True) or {}), # user-controlled (extra=\u0027allow\u0027)\n \u0027parent_id\u0027: parent_id,\n \u0027created_at\u0027: int(time.time()),\n \u0027updated_at\u0027: int(time.time()),\n }\n)\n```\n\nBecause `FolderModel` declares `user_id: str` as a real field (not just a form extra), any attacker-supplied `user_id` in the POST body is accepted by the model and persisted on the `Folder` row.\n\n## Attack Scenario\n\n1. Attacker discovers a victim\u0027s user ID. User UUIDs commonly leak via the user search endpoint (`GET /api/v1/users/search`, intentionally accessible to verified users for sharing UI), shared chat metadata, or channel member lists.\n2. Attacker sends:\n ```\n POST /api/v1/folders/\n {\n \"name\": \"Important: Click here\",\n \"user_id\": \"\u003cvictim_user_id\u003e\",\n \"meta\": {\"icon\": \"warning\"},\n \"data\": {...}\n }\n ```\n3. Pydantic accepts the extra `user_id` field (allowed by `extra=\u0027allow\u0027`).\n4. `insert_new_folder` spreads the form data over the server-set `\u0027user_id\u0027: user_id`, overwriting it with the attacker\u0027s value.\n5. The `Folder` row is persisted with `user_id = \u003cvictim_user_id\u003e`.\n6. The victim sees the attacker-planted folder in their UI on next load because `GET /api/v1/folders/` filters by the viewer\u0027s own `user_id`.\n\nThe attacker can repeat this to plant multiple folders, use crafted `name` values for phishing (\"Click here to recover account\" / \"Security alert\"), and abuse the `meta` and `data` fields to add visual elements that further mimic legitimate content.\n\n## Impact\n\n- Unauthorized write into victim\u0027s folder tree\n- Phishing surface: attacker-controlled `name`, `meta`, and `data` render in the victim\u0027s UI in a trusted context\n- DoS / spam: attacker can flood a victim with arbitrary folders; victim must manually delete each one\n- Attacker cannot read the folder back \u2014 all read paths filter by the caller\u0027s own `user_id` \u2014 so confidentiality is preserved, but integrity and trust are compromised\n\n## Preconditions\n\n- Attacker must have an authenticated account with `features.folders` permission (default for all users)\n- Attacker must know or guess the victim\u0027s user UUID (obtainable through various non-sensitive endpoints)",
"id": "PYSEC-2026-2735",
"modified": "2026-07-13T16:05:13.245306Z",
"published": "2026-07-13T15:15:41.715716Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-hr43-rjmr-7wmm"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44550"
},
{
"type": "PACKAGE",
"url": "https://github.com/open-webui/open-webui"
},
{
"type": "PACKAGE",
"url": "https://pypi.org/project/open-webui"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-hr43-rjmr-7wmm"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Open WebUI\u0027s Mass Assignment via Pydantic extra=\u0027allow\u0027 Allows Creating Folders in Other Users\u0027 Accounts"
}
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