CVE-2026-44550

Mass 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

1. 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.
2. Attacker sends:

   POST /api/v1/folders/
   {
     "name": "Important: Click here",
     "user_id": "<victim_user_id>",
     "meta": {"icon": "warning"},
     "data": {...}
   }
   

3. Pydantic accepts the extra user_id field (allowed by extra='allow').
4. insert_new_folder spreads the form data over the server-set 'user_id': user_id, overwriting it with the attacker's value.
5. The Folder row is persisted with user_id = <victim_user_id>.
6. The victim sees the attacker-planted folder in their UI on next load because GET /api/v1/folders/ filters by the viewer's own user_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.

Preconditions

• Attacker must have an authenticated account with features.folders permission (default for all users)
• Attacker must know or guess the victim's user UUID (obtainable through various non-sensitive endpoints)

• Unauthorized write into victim's folder tree
• Phishing surface: attacker-controlled name, meta, and data render 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

The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.

CVE-2026-44550 has a CVSS score of 5.0 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.9.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44550? CVE-2026-44550 is a medium-severity missing authorization vulnerability in open-webui (pip), affecting versions <= 0.8.12. It is fixed in 0.9.0. The application does not perform an authorization check before performing a sensitive operation.
2. How severe is CVE-2026-44550? CVE-2026-44550 has a CVSS score of 5.0 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of open-webui are affected by CVE-2026-44550? open-webui (pip) versions <= 0.8.12 is affected.
4. Is there a fix for CVE-2026-44550? Yes. CVE-2026-44550 is fixed in 0.9.0. Upgrade to this version or later.
5. Is CVE-2026-44550 exploitable, and should I be worried? Whether CVE-2026-44550 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-44550 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-44550? Upgrade open-webui to 0.9.0 or later.