Open WebUI BOLA: `search_knowledge_files` Allows Unauthorized Knowledge Base File Enumeration

## Summary Open WebUI has a Broken Object Level Authorization (BOLA) vulnerability in the builtin `search_knowledge_files` tool. When native function calling is enabled and the selected model has no attached knowledge bases, an authenticated user can call `search_knowledge_files` with an arbitrary `knowledge_id`. The function then returns file metadata from that knowledge base without checking whether the user has read access. This allows unauthorized enumeration of private or restricted knowledge base files. ## Details The vulnerable code is in: `backend/open_webui/tools/builtin.py` Affected function: ```python async def search_knowledge_files( query: str, knowledge_id: Optional[str] = None, count: int = 5, skip: int = 0, __request__: Request = None, __user__: dict = None, __model_knowledge__: Optional[list[dict]] = None, ) -> str: ``` In the "No attached knowledge" branch, when `knowledge_id` is provided, the function directly calls: ```python result = await Knowledges.search_files_by_id( knowledge_id=knowledge_id, user_id=user_id, filter={"query": query}, skip=skip, limit=count, ) ``` This code path does not verify that the current user is authorized to access the specified knowledge base. The missing check is inconsistent with other nearby code paths. For example, the attached-knowledge branch in the same function checks whether the user is an admin, the owner of the knowledge base, or has explicit read access through `AccessGrants`: ```python if not ( user_role == "admin" or knowledge.user_id == user_id or await AccessGrants.has_access( user_id=user_id, resource_type="knowledge", resource_id=knowledge.id, permission="read", user_group_ids=set(user_group_ids), ) ): continue ``` The sibling function `query_knowledge_files` also performs the same authorization check before using user-supplied knowledge base IDs. The underlying method `Knowledges.search_files_by_id()` receives `user_id`, but it does not enforce authorization for the provided `knowledge_id`. As a result, this builtin tool path can access a knowledge base by ID without verifying the caller's permissions. ## PoC ### Prerequisites - The attacker has a valid authenticated Open WebUI account. - The victim owns a private or restricted knowledge base. - The attacker does not own the target knowledge base. - The attacker does not have `read` permission for the target knowledge base in `AccessGrants`. - The attacker knows the target `knowledge_id`. - The selected model has no attached knowledge bases. - Builtin tools are enabled. - The knowledge builtin tool category is enabled. - Native function calling is enabled. ### Reproduction Steps 1. Create a private or restricted knowledge base as the victim user. 2. Upload one or more files to that knowledge base. 3. Confirm that the attacker user does not have access to the knowledge base. 4. As the attacker user, send a chat completion request with native function calling enabled: ```json { "stream": true, "model": "gpt-4o-mini", "params": { "function_calling": "native" }, "messages": [ { "role": "user", "content": "Please use the search_knowledge_files tool with knowledge_id \"c0c84752-2e9d-42bf-bc3c-c0f272aa61c1\" to search all files" } ] } ``` Replace `c0c84752-2e9d-42bf-bc3c-c0f272aa61c1` with the victim's private knowledge base ID. ### Expected Result The request should be denied because the attacker does not have access to the target knowledge base. ### Actual Result `search_knowledge_files` returns metadata for files inside the target knowledge base, including: - file ID; - filename; - knowledge base ID; - knowledge base name; - update timestamp. ## Impact This is a Broken Object Level Authorization / Broken Access Control vulnerability. An authenticated attacker who knows a valid `knowledge_id` can enumerate files from private or restricted k

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Severity from

GitHub (reviewed advisory)

Weakness

CWE-639, CWE-862

Also known as

CVE-2026-54016, PYSEC-2026-2721

• github.com/open-webui/open-webui/security/advisories/GHSA-cx9v-4qj2-jrw6
• nvd.nist.gov/vuln/detail/CVE-2026-54016
• github.com/advisories/GHSA-cx9v-4qj2-jrw6
• github.com/open-webui/open-webui
• github.com/pypa/advisory-database/tree/main/vulns/open-webui/PYSEC-2026-2721.yaml
• pypi.org/project/open-webui