GHSA-7R7X-GJVR-448G
Vulnerability from github – Published: 2026-07-24 17:02 – Updated: 2026-07-24 17:02Open WebUI upload metadata can add files to knowledge bases without write permission
Summary
Open WebUI's file upload background processing trusts the client-supplied metadata.knowledge_id value and inserts a knowledge_file association before validating that the uploading user has write access to the target knowledge base.
A verified user with only read access to a knowledge base can upload an arbitrary file and set metadata={"knowledge_id":"<target knowledge id>"}. The normal /api/v1/knowledge/{id}/file/add endpoint correctly requires knowledge-base write access, but the upload auto-link path bypasses that authorization check.
The immediate result is unauthorized modification of the target knowledge base's file membership. The attached attacker-controlled file becomes visible through /api/v1/knowledge/{id}/files, and readers/owners of that knowledge base can retrieve the file through the normal file endpoints because file access is derived from KnowledgeFile membership.
Affected Version
- Repository:
open-webui/open-webui - Tested source commit:
02dc3e689ceac915a870b373318b99c029ddf603 - Package version observed in
package.json:0.9.6 - Package name:
open-webui
Impact
A read-only knowledge-base collaborator can perform a write operation against that knowledge base by attaching arbitrary uploaded files.
Security impact:
- Unauthorized knowledge-base membership modification.
- Integrity impact on shared knowledge-base file listings.
- Attacker-controlled files become readable to other users who can read the target knowledge base.
- If an owner/admin later reprocesses or globally reindexes the knowledge base, the unauthorized file can be indexed into the knowledge collection, turning the membership bypass into RAG/content poisoning.
This is not an unauthenticated issue. It requires a verified Open WebUI account and a valid target knowledge-base ID. The clearest exploit path is a user who legitimately has read access to a knowledge base but not write access.
Source Evidence
The normal single-file knowledge add endpoint checks write permission before processing or inserting the relationship:
backend/open_webui/routers/knowledge.pyadd_file_to_knowledge_by_id- Lines 714-728 reject callers who are not owner, admin, or granted
writeaccess. - Lines 750-766 then process and insert the file only after that authorization gate.
The upload auto-link path does not perform the same check:
backend/open_webui/routers/files.pyprocess_uploaded_file- Lines 178-186 read
knowledge_idfrom upload metadata and immediately callKnowledges.add_file_to_knowledge_by_id(...). - Lines 187-192 call
process_file(... collection_name=knowledge_id ...)after the insert.
The model method inserts the relationship without validating the caller's write access to the knowledge base:
backend/open_webui/models/knowledge.pyadd_file_to_knowledge_by_id- Lines 646-677 create and commit a
KnowledgeFilerow for the suppliedknowledge_id,file_id, anduser_id.
The later vector write check exists, but it runs too late:
backend/open_webui/routers/retrieval.pyprocess_file- Lines 1587-1592 call
_validate_collection_access(..., access_type='write')when a collection is supplied.
Because the unauthorized KnowledgeFile row is already committed before that check runs, the failed vector processing does not undo the knowledge-base file association. The upload code catches the exception at backend/open_webui/routers/files.py lines 194-195 and logs a warning while leaving the row in place.
The unauthorized relationship affects file access decisions:
backend/open_webui/utils/access_control/files.pyhas_access_to_file- Lines 41-53 grant file access when a file is associated with a knowledge base the user can access.
So once the attacker's file is inserted into the target KnowledgeFile table, target knowledge-base readers/owners can see and fetch that file through normal knowledge/file routes.
Reproduction Steps
Use a local Open WebUI instance with two verified users:
- As user
owner, create a knowledge base. - Grant user
readerread access to the knowledge base, but do not grant write access. - As
reader, confirm the normal add-file endpoint is blocked:
POST /api/v1/knowledge/<knowledge_id>/file/add
Authorization: Bearer <reader token>
Content-Type: application/json
{"file_id":"<reader-owned-file-id>"}
Expected and observed behavior for the normal route: it rejects the request because reader lacks knowledge-base write access.
- As
reader, upload a new file with the same target knowledge ID embedded in upload metadata:
POST /api/v1/files/?process=true&process_in_background=false
Authorization: Bearer <reader token>
Content-Type: multipart/form-data
file=@attacker-note.txt
metadata={"knowledge_id":"<knowledge_id>"}
- Observe that the upload request succeeds and returns the uploaded file record.
- As
owner, request the knowledge-base files:
GET /api/v1/knowledge/<knowledge_id>/files
Authorization: Bearer <owner token>
- Observe that
attacker-note.txtappears in the target knowledge base even thoughreaderdid not have write access. - As
owner, request the file content:
GET /api/v1/files/<attacker_file_id>/content
Authorization: Bearer <owner token>
- Observe that the file is retrievable because
has_access_to_filederives access from the unauthorized knowledge-base membership.
Expected Behavior
The upload auto-link path should enforce the same authorization contract as /api/v1/knowledge/{id}/file/add:
- The target knowledge base must exist.
- The caller must be the knowledge owner, an admin, or have
writeaccess. - The supplied
directory_id, if present, must belong to the target knowledge base. - The
KnowledgeFileassociation should only be inserted after authorization and processing succeed.
Actual Behavior
metadata.knowledge_id causes Knowledges.add_file_to_knowledge_by_id(...) to insert a KnowledgeFile row before write authorization is checked. The later collection write validation can fail, but the unauthorized membership row remains committed.
Suggested Fix
Move knowledge-base authorization before the insert in the upload auto-link path. The upload path should share the same write-access and directory validation logic used by the dedicated knowledge endpoints.
One safe pattern:
- Load the target knowledge base.
- Require owner/admin/write access before calling
Knowledges.add_file_to_knowledge_by_id. - Validate that
directory_id, if supplied, belongs to the same knowledge base. - Run vector processing before inserting the membership row, or wrap processing plus insertion in a transaction/compensating cleanup so a denied or failed process cannot leave a stale unauthorized row.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "open-webui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.10.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-59217"
],
"database_specific": {
"cwe_ids": [
"CWE-862",
"CWE-863"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-24T17:02:14Z",
"nvd_published_at": "2026-07-09T17:17:02Z",
"severity": "MODERATE"
},
"details": "# Open WebUI upload metadata can add files to knowledge bases without write permission\n\n## Summary\n\nOpen WebUI\u0027s file upload background processing trusts the client-supplied `metadata.knowledge_id` value and inserts a `knowledge_file` association before validating that the uploading user has write access to the target knowledge base.\n\nA verified user with only read access to a knowledge base can upload an arbitrary file and set `metadata={\"knowledge_id\":\"\u003ctarget knowledge id\u003e\"}`. The normal `/api/v1/knowledge/{id}/file/add` endpoint correctly requires knowledge-base write access, but the upload auto-link path bypasses that authorization check.\n\nThe immediate result is unauthorized modification of the target knowledge base\u0027s file membership. The attached attacker-controlled file becomes visible through `/api/v1/knowledge/{id}/files`, and readers/owners of that knowledge base can retrieve the file through the normal file endpoints because file access is derived from `KnowledgeFile` membership.\n\n## Affected Version\n\n- Repository: `open-webui/open-webui`\n- Tested source commit: `02dc3e689ceac915a870b373318b99c029ddf603`\n- Package version observed in `package.json`: `0.9.6`\n- Package name: `open-webui`\n\n## Impact\n\nA read-only knowledge-base collaborator can perform a write operation against that knowledge base by attaching arbitrary uploaded files.\n\nSecurity impact:\n\n- Unauthorized knowledge-base membership modification.\n- Integrity impact on shared knowledge-base file listings.\n- Attacker-controlled files become readable to other users who can read the target knowledge base.\n- If an owner/admin later reprocesses or globally reindexes the knowledge base, the unauthorized file can be indexed into the knowledge collection, turning the membership bypass into RAG/content poisoning.\n\nThis is not an unauthenticated issue. It requires a verified Open WebUI account and a valid target knowledge-base ID. The clearest exploit path is a user who legitimately has read access to a knowledge base but not write access.\n\n## Source Evidence\n\nThe normal single-file knowledge add endpoint checks write permission before processing or inserting the relationship:\n\n- `backend/open_webui/routers/knowledge.py`\n- `add_file_to_knowledge_by_id`\n- Lines 714-728 reject callers who are not owner, admin, or granted `write` access.\n- Lines 750-766 then process and insert the file only after that authorization gate.\n\nThe upload auto-link path does not perform the same check:\n\n- `backend/open_webui/routers/files.py`\n- `process_uploaded_file`\n- Lines 178-186 read `knowledge_id` from upload metadata and immediately call `Knowledges.add_file_to_knowledge_by_id(...)`.\n- Lines 187-192 call `process_file(... collection_name=knowledge_id ...)` after the insert.\n\nThe model method inserts the relationship without validating the caller\u0027s write access to the knowledge base:\n\n- `backend/open_webui/models/knowledge.py`\n- `add_file_to_knowledge_by_id`\n- Lines 646-677 create and commit a `KnowledgeFile` row for the supplied `knowledge_id`, `file_id`, and `user_id`.\n\nThe later vector write check exists, but it runs too late:\n\n- `backend/open_webui/routers/retrieval.py`\n- `process_file`\n- Lines 1587-1592 call `_validate_collection_access(..., access_type=\u0027write\u0027)` when a collection is supplied.\n\nBecause the unauthorized `KnowledgeFile` row is already committed before that check runs, the failed vector processing does not undo the knowledge-base file association. The upload code catches the exception at `backend/open_webui/routers/files.py` lines 194-195 and logs a warning while leaving the row in place.\n\nThe unauthorized relationship affects file access decisions:\n\n- `backend/open_webui/utils/access_control/files.py`\n- `has_access_to_file`\n- Lines 41-53 grant file access when a file is associated with a knowledge base the user can access.\n\nSo once the attacker\u0027s file is inserted into the target `KnowledgeFile` table, target knowledge-base readers/owners can see and fetch that file through normal knowledge/file routes.\n\n## Reproduction Steps\n\nUse a local Open WebUI instance with two verified users:\n\n1. As user `owner`, create a knowledge base.\n2. Grant user `reader` read access to the knowledge base, but do not grant write access.\n3. As `reader`, confirm the normal add-file endpoint is blocked:\n\n```http\nPOST /api/v1/knowledge/\u003cknowledge_id\u003e/file/add\nAuthorization: Bearer \u003creader token\u003e\nContent-Type: application/json\n\n{\"file_id\":\"\u003creader-owned-file-id\u003e\"}\n```\n\nExpected and observed behavior for the normal route: it rejects the request because `reader` lacks knowledge-base write access.\n\n4. As `reader`, upload a new file with the same target knowledge ID embedded in upload metadata:\n\n```http\nPOST /api/v1/files/?process=true\u0026process_in_background=false\nAuthorization: Bearer \u003creader token\u003e\nContent-Type: multipart/form-data\n\nfile=@attacker-note.txt\nmetadata={\"knowledge_id\":\"\u003cknowledge_id\u003e\"}\n```\n\n5. Observe that the upload request succeeds and returns the uploaded file record.\n6. As `owner`, request the knowledge-base files:\n\n```http\nGET /api/v1/knowledge/\u003cknowledge_id\u003e/files\nAuthorization: Bearer \u003cowner token\u003e\n```\n\n7. Observe that `attacker-note.txt` appears in the target knowledge base even though `reader` did not have write access.\n8. As `owner`, request the file content:\n\n```http\nGET /api/v1/files/\u003cattacker_file_id\u003e/content\nAuthorization: Bearer \u003cowner token\u003e\n```\n\n9. Observe that the file is retrievable because `has_access_to_file` derives access from the unauthorized knowledge-base membership.\n\n## Expected Behavior\n\nThe upload auto-link path should enforce the same authorization contract as `/api/v1/knowledge/{id}/file/add`:\n\n- The target knowledge base must exist.\n- The caller must be the knowledge owner, an admin, or have `write` access.\n- The supplied `directory_id`, if present, must belong to the target knowledge base.\n- The `KnowledgeFile` association should only be inserted after authorization and processing succeed.\n\n## Actual Behavior\n\n`metadata.knowledge_id` causes `Knowledges.add_file_to_knowledge_by_id(...)` to insert a `KnowledgeFile` row before write authorization is checked. The later collection write validation can fail, but the unauthorized membership row remains committed.\n\n## Suggested Fix\n\nMove knowledge-base authorization before the insert in the upload auto-link path. The upload path should share the same write-access and directory validation logic used by the dedicated knowledge endpoints.\n\nOne safe pattern:\n\n1. Load the target knowledge base.\n2. Require owner/admin/write access before calling `Knowledges.add_file_to_knowledge_by_id`.\n3. Validate that `directory_id`, if supplied, belongs to the same knowledge base.\n4. Run vector processing before inserting the membership row, or wrap processing plus insertion in a transaction/compensating cleanup so a denied or failed process cannot leave a stale unauthorized row.",
"id": "GHSA-7r7x-gjvr-448g",
"modified": "2026-07-24T17:02:14Z",
"published": "2026-07-24T17:02:14Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-7r7x-gjvr-448g"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59217"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/pull/26001"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/commit/b7626f05fb92b24ab923ad81a037071ebd5623d1"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Open WebUI: Upload `metadata.knowledge_id` bypasses the knowledge-base write-access check (read-only users can add files to KB)"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.