# CVE-2026-45399: open-webui PrivEsc β€” Fixed in 0.9.0 🐍 🐍 PyPI Not in CISA KEV HIGH severity # CVE-2026-45399 β€” open-webui HIGH [Fix: open-webui/open-webui#23454](https://github.com/open-webui/open-webui/pull/23454) CVE-2026-45399 is a high-severity (CVSS 7.1) CWE-862 vulnerability in open-webui. A fix is available for open-webui β€” see the affected versions and patch details below. Open WebUI: Low-privilege authenticated users can enumerate and stop global background tasks, causing system-wide chat disruption Also known as[GHSA-8jjp-r2w2-4v22](/vulnerability/GHSA-8jjp-r2w2-4v22)PYSEC-2026-2714 Published May 15, 2026 Updated Oct 28, 2026 Affected 1 pkg Patched 1 / 1 Exploits None indexed Exploitation data as of Nov 8, 2026 Β· OSV.dev, NVD, FIRST.org (EPSS) ## Exploitation Status ### Proof-of-concept exploit code exists - CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation. Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45399. ## EPSS Exploitation Probability [via FIRST.org β†—](https://www.first.org/epss/) 0.3%probability of exploitation in next 30 days Lower Risk0.00% Lower risk than most CVEs19th percentile β€” riskier than 19% of all scored CVEsHighest risk 0.00%0.30%0.59%0.89%0.0%0.3%Jun 26Sep 26Nov 26 Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/). ## How urgent is this, really ## Where this sits among everything scored ## Real-World Exposure 1 pkg affected 🐍`open-webui` Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages β€” download data is not available via public APIs for these ecosystems. ## Description #### Summary 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' active tasks. This is a real authorization vulnerability affecting integrity and usability in multi-user deployments. #### Details Open 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. As a result, a normal authenticated user can enumerate active global task IDs and stop tasks belonging to other users. Root cause: 1. Route authorization is too weak. In `backend/open_webui/main.py`, both endpoints only require `get_verified_user`: ``` @app.post('/api/tasks/stop/{task_id}') async def stop_task_endpoint(request: Request, task_id: str, user=Depends(get_verified_user)): result = await stop_task(request.app.state.redis, task_id) @app.get('/api/tasks') async def list_tasks_endpoint(request: Request, user=Depends(get_verified_user)): return {'tasks': await list_tasks(request.app.state.redis)} ``` `get_verified_user` accepts both `user` and `admin` roles in `backend/open_webui/utils/auth.py`. 1. The helper operates on a global namespace. In `backend/open_webui/tasks.py`, task listing is global: ``` async def list_tasks(redis): if redis: return await redis_list_tasks(redis) return list(tasks.keys()) ``` In `backend/open_webui/tasks.py`, task stopping is by raw `task_id`: ``` async def stop_task(redis, task_id: str): if redis: item_id = await redis.hget(REDIS_TASKS_KEY, task_id) await redis_send_command(redis, {'action': 'stop', 'task_id': task_id}) await redis_cleanup_task(redis, task_id, item_id or None) ``` There is no owner check, no `user_id` check, and no mapping from `task_id` back to the current caller before stop or cleanup. This 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. Relevant code references: - `backend/open_webui/main.py:1975` - `backend/open_webui/main.py:1984` - `backend/open_webui/main.py:1989` - `backend/open_webui/tasks.py:127` - `backend/open_webui/tasks.py:145` - `backend/open_webui/utils/auth.py:415` Suggested remediation: - Store task ownership metadata such as `user_id` and `chat_id`, then enforce owner-only access for non-admin users - Suggested implementation locations: - `backend/open_webui/main.py`: add authentication checks for `/api/tasks` and `/api/tasks/stop/{task_id}` - `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 #### PoC Preconditions: - Default `main` branch deployment - Authentication enabled - Two normal user accounts, or any multi-user deployment where the attacker has one authenticated non-admin account - At least one task actively running for another user This does not require any weakened security settings. PoC objective: 1. Show that a non-admin user can see global active task IDs that are not their own 2. Show that the same user can stop another user's active task Reproduction steps: #### Step 1. Victim starts a long-running task Using the UI, User A starts a long response generation or another background task and leaves it running. Expected security model: User B should not be able to see or control User A's task. #### Step 2. Attacker enumerates global task IDs Using User B's authenticated token: ``` curl -i -H "Authorization: Bearer " http:///api/tasks ``` Expected result: - only User B's own task IDs should be returned, or - the endpoint should be admin-only Actual result: the response returns the global active task list. Example response shape: ``` {"tasks":["",""]} ``` This exposes task IDs belonging to other users. #### Step 3. Attacker stops a foreign task Pick a task ID that belongs to User A and send: ``` curl -i -X POST -H "Authorization: Bearer " http:///api/tasks/stop/ ``` Expected result: - `403 Forbidden`, or - `404 Not Found` for non-owned tasks, or - admin-only access Actual result: the server accepts the request and attempts to stop the foreign task. Example response shape: ``` {"status":true,"message":"Task stopped."} ``` #### Step 4. Observe boundary violation User A's running task is interrupted or disappears from the active task set even though User B does not own it. What actions become possible that should not be possible: - enumerate globally active task IDs across users - cancel another user's in-progress generation or background work - repeat this for every returned task ID, causing broad cross-user disruption Copy-paste PoC summary: 1. Enumerate all active tasks as a normal non-admin user ``` curl -s -H "Authorization: Bearer " http:///api/tasks ``` 1. Stop a task that does not belong to that user ``` curl -s -X POST -H "Authorization: Bearer " http:///api/tasks/stop/ ``` #### Impact Type of vulnerability: broken object-level authorization affecting a global runtime control-plane endpoint. Who is impacted: - all users in a multi-user Open WebUI deployment - any user currently running a background task, especially chat generation tasks - administrators indirectly, because normal users can disrupt system-wide usage without admin privileges Direct impact: - cross-user task ID disclosure - cross-user task cancellation Practical impact: - interruption of long-running chat responses - interruption of background indexing or ingestion tasks associated with shared runtime jobs - one ordinary authenticated low-privilege user can continuously poll `/api/tasks` and immediately cancel every newly created active task - with a simple loop or script, this becomes a practical persistent denial-of-service against chat usage for all users on the instance - in a multi-user deployment, normal users may be unable to complete any chat generation while the attacker continues polling and cancelling tasks Why severity is meaningful: - privileges required: low, only an authenticated non-admin account - scope: cross-user - impact class: integrity and availability - exploitation complexity: low once logged in This 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. ### Resolution Fixed 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). The 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`: - `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. - 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. CVE-2025-63681 was a prior disclosure of the same authorization gap against v0.6.33; the fix in v0.9.0 also resolves that. Users on `>= 0.9.0` are not affected. ## Affected Packages 1 total 1 fixed Ecosystem Package Vulnerable range Fix 🐍PyPI `open-webui` all versions 0.9.0`pip install --upgrade 'open-webui==0.9.0'` ## Affected Products 1 product Β· 1 configurations Application `open webui`openwebui < 0.9.0 range ## Detection & mitigation playbook Open-source dependency 1. ### Detect Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for open-webui, including transitive dependencies β€” a direct dependency you never call can still pull in a vulnerable version. 2. ### Fix Update open-webui to 0.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range β€” O3 confirms CVE-2026-45399 is resolved across your whole dependency graph. 3. ### Workarounds Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs β€” a default left in place is what makes this reachable. ## Frequently Asked Questions \### Summary 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' active tasks. This is a real authorization vulnerability affecting integrity and usability in multi-user deployments. ### Details Open 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 a O3 Security Β· Impact-Aware SCA ### Is CVE-2026-45399 in your dependencies? Find it across PyPI, including transitive dependencies. [Scan my dependencies](/book-demo) [How O3 SCA works](/impact-aware-sca)