{"id":"CVE-2026-44557","aliases":["GHSA-6c2x-gcp3-gp73","PYSEC-2026-2707"],"title":"Open WebUI vulnerable to Global Knowledge Base Enumeration via knowledge-bases Meta-Collection","summary":"Open WebUI vulnerable to Global Knowledge Base Enumeration via knowledge-bases Meta-Collection","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","vendor":"open-webui","product":"open-webui","ecosystem":"pip","affected":["open-webui < 0.9.0"],"patched":["open-webui 0.9.0"],"published":"2026-05-08","updated":"2026-07-13","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-6c2x-gcp3-gp73","references":[{"url":"https://github.com/open-webui/open-webui/security/advisories/GHSA-6c2x-gcp3-gp73"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44557"},{"url":"https://github.com/open-webui/open-webui"}],"tags":["osv","pip"],"epss":0.00221,"epssPercentile":0.1285,"ingestedAt":"2026-07-13T18:57:53.782Z","slug":"CVE-2026-44557","body":"## Overview\n\n# Global Knowledge Base Enumeration via knowledge-bases Meta-Collection\n\n## Affected Component\n\nRetrieval collection access validation:\n- `backend/open_webui/routers/retrieval.py` (lines 2330-2355, `_validate_collection_access`)\n- `backend/open_webui/routers/retrieval.py` (query endpoints, e.g. `POST /query/doc`)\n\n## Affected Versions\n\nCurrent main branch (commit `6fdd19bf1`) and likely all versions with the knowledge base subsystem.\n\n## Description\n\nThe `_validate_collection_access` function uses an incomplete allowlist that only enforces ownership checks for collections matching `user-memory-*` and `file-*` patterns. All other collection names pass through unchecked — including the system-level `knowledge-bases` meta-collection, which stores the IDs, names, and descriptions of every knowledge base on the instance.\n\nAny authenticated user can query this meta-collection directly via the retrieval query endpoints to obtain a global index of all knowledge bases across all users.\n\n```python\n# retrieval.py:2330-2355 — incomplete collection allowlist\ndef _validate_collection_access(user, collection_name, ...):\n    if collection_name.startswith('user-memory-'):\n        # Check user-memory ownership\n        ...\n    elif collection_name.startswith('file-'):\n        # Check file access\n        ...\n    # Everything else (including \"knowledge-bases\") passes through unchecked\n```\n\nThis finding is the enabler for the KB destruction (`process/web`), KB content injection (`process/file`), and RAG vector search access bypass findings — all of which require knowing a target KB's UUID. Without this enumeration, UUIDs are random and practically unguessable; with it, UUIDs across the entire instance are trivially obtained.\n\n## CVSS 3.1 Breakdown\n\n| Metric | Value | Rationale |\n|--------|-------|-----------|\n| Attack Vector | Network (N) | Exploited remotely via API call |\n| Attack Complexity | Low (L) | Single API call |\n| Privileges Required | Low (L) | Requires any authenticated user account |\n| User Interaction | None (N) | No victim interaction required |\n| Scope | Unchanged (U) | Impact within the knowledge base boundary |\n| Confidentiality | Low (L) | Discloses KB metadata (IDs, names, descriptions) across all users |\n| Integrity | None (N) | No direct data modification |\n| Availability | None (N) | No denial of service |\n\n## Attack Scenario\n\n1. Attacker (any authenticated user) sends:\n   ```\n   POST /api/v1/retrieval/query/doc\n   {\n     \"collection_name\": \"knowledge-bases\",\n     \"query\": \"confidential\"\n   }\n   ```\n2. `_validate_collection_access` does not recognize the `knowledge-bases` prefix and lets the request pass.\n3. The vector search returns the most relevant documents from the meta-collection — knowledge base records including their UUIDs, names, and descriptions — across all users on the instance.\n4. Attacker varies the query to enumerate more KBs: `\"project\"`, `\"internal\"`, `\"private\"`, etc.\n5. Attacker now has a full target list for subsequent attacks (destruction, poisoning, content extraction).\n\n## Impact\n\n- **Information disclosure:** KB names and descriptions may reveal sensitive project names, internal initiatives, or user activities\n- **Enabler for other attacks:** Unlocks the following findings by supplying the required target UUIDs:\n  - KB destruction/poisoning via `process/web`\n  - Cross-user content injection via `process/file`\n  - RAG vector search access bypass in `retrieval/utils.py`\n- Transforms these from theoretical (requires UUID guessing) to trivially exploitable (UUIDs enumerable)\n\n## Preconditions\n\n- Attacker must have a valid user account\n\n## Affected packages\n\n- `open-webui < 0.9.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `open-webui 0.9.0`","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}