{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "0FB90EC3-1665-446E-AA35-4AEC207A2F3B",
              "versionEndExcluding": "0.9.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, any authenticated user with low privileges can enumerate active background tasks across the system and stop tasks belonging to other users via the GET /api/tasks and POST /api/tasks/stop/{task_id} methods. This allows a casual user to disrupt system-wide chat usage by continuously canceling other users\u0027 active tasks. This is a real authorization vulnerability affecting integrity and usability in multi-user deployments. This vulnerability is fixed in 0.9.0."
    }
  ],
  "id": "CVE-2026-45399",
  "lastModified": "2026-05-19T03:08:17.500",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.2,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-15T20:16:48.950",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-8jjp-r2w2-4v22"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-8jjp-r2w2-4v22"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.8.12"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45399"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-14T20:26:49Z",
    "nvd_published_at": "2026-05-15T20:16:48Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nAny authenticated user with low privileges can enumerate active background tasks across the system and stop tasks belonging to other users via the GET /api/tasks and POST /api/tasks/stop/{task_id} methods. This allows a casual user to disrupt system-wide chat usage by continuously canceling other users\u0027 active tasks. This is a real authorization vulnerability affecting integrity and usability in multi-user deployments.\n\n\n### Details\nOpen WebUI exposes `GET /api/tasks` and `POST /api/tasks/stop/{task_id}` to any verified user. These endpoints operate on a global task namespace and accept raw `task_id` values without checking whether the task belongs to the current caller.\n\nAs a result, a normal authenticated user can enumerate active global task IDs and stop tasks belonging to other users.\n\nRoot cause:\n\n1. Route authorization is too weak.\n\nIn `backend/open_webui/main.py`, both endpoints only require `get_verified_user`:\n\n```python\n@app.post(\u0027/api/tasks/stop/{task_id}\u0027)\nasync def stop_task_endpoint(request: Request, task_id: str, user=Depends(get_verified_user)):\n    result = await stop_task(request.app.state.redis, task_id)\n\n@app.get(\u0027/api/tasks\u0027)\nasync def list_tasks_endpoint(request: Request, user=Depends(get_verified_user)):\n    return {\u0027tasks\u0027: await list_tasks(request.app.state.redis)}\n```\n\n`get_verified_user` accepts both `user` and `admin` roles in `backend/open_webui/utils/auth.py`.\n\n2. The helper operates on a global namespace.\n\nIn `backend/open_webui/tasks.py`, task listing is global:\n\n```python\nasync def list_tasks(redis):\n    if redis:\n        return await redis_list_tasks(redis)\n    return list(tasks.keys())\n```\n\nIn `backend/open_webui/tasks.py`, task stopping is by raw `task_id`:\n\n```python\nasync def stop_task(redis, task_id: str):\n    if redis:\n        item_id = await redis.hget(REDIS_TASKS_KEY, task_id)\n        await redis_send_command(redis, {\u0027action\u0027: \u0027stop\u0027, \u0027task_id\u0027: task_id})\n        await redis_cleanup_task(redis, task_id, item_id or None)\n```\n\nThere is no owner check, no `user_id` check, and no mapping from `task_id` back to the current caller before stop or cleanup.\n\nThis also appears unintended because the codebase already has a scoped route, `GET /api/tasks/chat/{chat_id}`, which checks whether the chat belongs to the current user before returning task IDs.\n\nRelevant code references:\n- `backend/open_webui/main.py:1975`\n- `backend/open_webui/main.py:1984`\n- `backend/open_webui/main.py:1989`\n- `backend/open_webui/tasks.py:127`\n- `backend/open_webui/tasks.py:145`\n- `backend/open_webui/utils/auth.py:415`\n\nSuggested remediation:\n- Store task ownership metadata such as `user_id` and `chat_id`, then enforce owner-only access for non-admin users\n- Suggested implementation locations:\n  - `backend/open_webui/main.py`: add authentication checks for `/api/tasks` and `/api/tasks/stop/{task_id}`\n  - `backend/open_webui/tasks.py`: add support for storing/querying task ownership metadata such as `user_id` and `chat_id`, and support owner-scoped listing/stopping\n\n\n\n### PoC\nPreconditions:\n\n- Default `main` branch deployment\n- Authentication enabled\n- Two normal user accounts, or any multi-user deployment where the attacker has one authenticated non-admin account\n- At least one task actively running for another user\n\nThis does not require any weakened security settings.\n\nPoC objective:\n\n1. Show that a non-admin user can see global active task IDs that are not their own\n2. Show that the same user can stop another user\u0027s active task\n\nReproduction steps:\n\n#### Step 1. Victim starts a long-running task\n\nUsing the UI, User A starts a long response generation or another background task and leaves it running.\n\nExpected security model:\nUser B should not be able to see or control User A\u0027s task.\n\n#### Step 2. Attacker enumerates global task IDs\n\nUsing User B\u0027s authenticated token:\n\n```bash\ncurl -i -H \"Authorization: Bearer \u003cUSER_B_TOKEN\u003e\" http://\u003copen-webui-host\u003e/api/tasks\n```\n\nExpected result:\n\n- only User B\u0027s own task IDs should be returned, or\n- the endpoint should be admin-only\n\nActual result:\nthe response returns the global active task list.\n\nExample response shape:\n\n```json\n{\"tasks\":[\"\u003ctask-id-a\u003e\",\"\u003ctask-id-b\u003e\"]}\n```\n\nThis exposes task IDs belonging to other users.\n\n#### Step 3. Attacker stops a foreign task\n\nPick a task ID that belongs to User A and send:\n\n```bash\ncurl -i -X POST -H \"Authorization: Bearer \u003cUSER_B_TOKEN\u003e\" http://\u003copen-webui-host\u003e/api/tasks/stop/\u003cFOREIGN_TASK_ID\u003e\n```\n\nExpected result:\n\n- `403 Forbidden`, or\n- `404 Not Found` for non-owned tasks, or\n- admin-only access\n\nActual result:\nthe server accepts the request and attempts to stop the foreign task.\n\nExample response shape:\n\n```json\n{\"status\":true,\"message\":\"Task \u003cFOREIGN_TASK_ID\u003e stopped.\"}\n```\n\n#### Step 4. Observe boundary violation\n\nUser A\u0027s running task is interrupted or disappears from the active task set even though User B does not own it.\n\nWhat actions become possible that should not be possible:\n\n- enumerate globally active task IDs across users\n- cancel another user\u0027s in-progress generation or background work\n- repeat this for every returned task ID, causing broad cross-user disruption\n\nCopy-paste PoC summary:\n\n1. Enumerate all active tasks as a normal non-admin user\n\n```bash\ncurl -s -H \"Authorization: Bearer \u003cUSER_B_TOKEN\u003e\" http://\u003copen-webui-host\u003e/api/tasks\n```\n\n2. Stop a task that does not belong to that user\n\n```bash\ncurl -s -X POST -H \"Authorization: Bearer \u003cUSER_B_TOKEN\u003e\" http://\u003copen-webui-host\u003e/api/tasks/stop/\u003cFOREIGN_TASK_ID\u003e\n```\n\n### Impact\nType of vulnerability:\nbroken object-level authorization affecting a global runtime control-plane endpoint.\n\nWho is impacted:\n\n- all users in a multi-user Open WebUI deployment\n- any user currently running a background task, especially chat generation tasks\n- administrators indirectly, because normal users can disrupt system-wide usage without admin privileges\n\nDirect impact:\n\n- cross-user task ID disclosure\n- cross-user task cancellation\n\nPractical impact:\n\n- interruption of long-running chat responses\n- interruption of background indexing or ingestion tasks associated with shared runtime jobs\n- one ordinary authenticated low-privilege user can continuously poll `/api/tasks` and immediately cancel every newly created active task\n- with a simple loop or script, this becomes a practical persistent denial-of-service against chat usage for all users on the instance\n- in a multi-user deployment, normal users may be unable to complete any chat generation while the attacker continues polling and cancelling tasks\n\nWhy severity is meaningful:\n\n- privileges required: low, only an authenticated non-admin account\n- scope: cross-user\n- impact class: integrity and availability\n- exploitation complexity: low once logged in\n\nThis is not full account takeover or privilege escalation, but it enables platform-wide operational disruption from a low-privilege account. In practice, sustained exploitation can make chat functionality effectively unusable for other users on the system.\n\n## Resolution\n\nFixed in commit [e7ff4768f](https://github.com/open-webui/open-webui/commit/e7ff4768f8ffe1924b4576381c9e45e8a64350e4) ([#23454](https://github.com/open-webui/open-webui/pull/23454), \"Add ownership checks to global task endpoints\"), first released in **v0.9.0** (Apr 2026).\n\nThe fix takes a simpler approach than per-task ownership tracking, which would have required a schema change to attribute every task to a `user_id`:\n\n- `GET /api/tasks` and `POST /api/tasks/stop/{task_id}` are restricted to admin-only via `Depends(get_admin_user)`. Cross-user enumeration and termination are no longer reachable from a non-admin account.\n- A new scoped `POST /api/tasks/chat/{chat_id}/stop` endpoint covers the legitimate non-admin use case (a user stopping their own in-progress generation), reusing the same chat-ownership check the existing `GET /api/tasks/chat/{chat_id}` already enforces.\n\nCVE-2025-63681 was a prior disclosure of the same authorization gap against v0.6.33; the fix in v0.9.0 also resolves that.\n\nUsers on `\u003e= 0.9.0` are not affected.",
  "id": "GHSA-8jjp-r2w2-4v22",
  "modified": "2026-05-15T23:54:50Z",
  "published": "2026-05-14T20:26:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-8jjp-r2w2-4v22"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45399"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/pull/23454"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/commit/e7ff4768f8ffe1924b4576381c9e45e8a64350e4"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/releases/tag/v0.9.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI: Low-privilege authenticated users can enumerate and stop global background tasks, causing system-wide chat disruption"
}