CVE-2026-45666 is a medium-severity (CVSS 6.5) CWE-639 vulnerability in open-webui. A fix is available for open-webui — see the affected versions and patch details below.
Open WebUI: Indirect Object Reference (IDOR) in user notes
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-2026-45666.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
open-webuiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The API /api/v1/notes/{note_id} endpoint lacks proper authorization checks, allowing authenticated users to retrieve notes belonging to other users by guessing or enumerating UUIDs. This results in unauthorized disclosure of potentially sensitive or private user data.
Details
- if notes is enabled from UI (Settings >> General >> Features >> Notes (Beta))
- From API, attacker can access other user notes
- if notes is disabled from UI (Settings >> General >> Features >> Notes (Beta))
- Then attacker can enable the notes from /api/config and access other user notes
PoC
-
Step 1: Log in to the application as a valid user (User A).
-
Step 2: Intercept or inspect the response from the endpoint GET /api/config.
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Step 3: Observe the field "enable_notes": false in the JSON response.
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Step 4: Manually change "enable_notes" to true using browser DevTools or by intercepting and modifying the response via a proxy like Burp Suite. (Please note, the occurrence of this API comes twice, hence modification needs to be made twice as well.)
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Step 5: Observe the loaded frontend application; the previously hidden notes form will now be visible.
- Step 6: Again, click on any note, intercept the request, and Replace the note_id in the URL with a different note ID known to belong to another user (e.g., by guessing or bruteforcing).
- Step 7: Send the modified request while remaining logged in as User A.
- Step 8: Observe that the server returns the content of another user's note, confirming unauthorized access.
Impact
- Unauthorized access to user-created notes
- Possible exposure of confidential or sensitive uploaded data
- Violation of user privacy and data isolation
- High risk of legal or compliance breaches in regulated environments
Resolution
Fixed in commit de3317e26, first released in v0.8.11 (Mar 2026). All per-id note endpoints (GET /api/v1/notes/{id}, POST /api/v1/notes/{id}/update, POST /api/v1/notes/{id}/access/update, deletion) now enforce ownership: the handler fetches the note, then requires the caller to be admin, the note owner, or have an AccessGrants grant for the appropriate permission (read for retrieval, write for mutation). A non-owner with no grant receives 403.
Users on >= 0.8.11 are not affected.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | open-webui | all versions | 0.8.11pip install --upgrade 'open-webui==0.8.11' |
Affected Products
open webuiopenwebuiDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for open-webui, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update open-webui to 0.8.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45666 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-45666 in your dependencies?
Find it across PyPI, including transitive dependencies.