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CVE-2026-45666 open-webui CVE debrief

Open WebUI versions prior to 0.8.11 contain an authorization bypass vulnerability in the `/api/v1/notes/{note_id}` API endpoint. Authenticated users can retrieve notes belonging to other users by guessing or enumerating UUIDs, resulting in unauthorized disclosure of potentially sensitive user data. The vulnerability stems from missing authorization checks on the note retrieval endpoint. This issue was published by NVD on 2026-05-15 and last modified on 2026-05-19. The vendor has released version 0.8.11 to address this flaw.

Vendor
open-webui
Product
Unknown
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-15
Original CVE updated
2026-05-19
Advisory published
2026-05-15
Advisory updated
2026-05-19

Who should care

Organizations running self-hosted Open WebUI instances with multiple users, particularly those storing sensitive or private information in user notes. Security teams responsible for AI platform infrastructure and application security engineers reviewing API authorization patterns.

Technical summary

The `/api/v1/notes/{note_id}` endpoint in Open WebUI prior to 0.8.11 fails to validate that the requesting authenticated user owns the requested note resource. Attackers with valid credentials can iterate through UUID values to access arbitrary notes. The fix in version 0.8.11 adds proper authorization checks to ensure users can only retrieve their own notes.

Defensive priority

medium

Recommended defensive actions

  • Upgrade Open WebUI to version 0.8.11 or later to remediate the authorization bypass vulnerability
  • Review API endpoint access controls for other resources that may use UUID-based identification without proper ownership verification
  • Monitor access logs for unusual patterns of note retrieval requests that may indicate attempted exploitation
  • Implement additional authorization checks at the application layer to verify note ownership before returning data
  • Consider implementing rate limiting on note retrieval endpoints to reduce the feasibility of UUID enumeration attacks

Evidence notes

NVD records indicate the vulnerability affects Open WebUI versions prior to 0.8.11, with CVSS 3.1 vector AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N. The GitHub Security Advisory (GHSA-x3qm-p8hr-3c3h) confirms the issue and provides patch information. CPE criteria: cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*, vulnerable versions exclude 0.8.11 and above. CWE-639 (Authorization Bypass Through User-Controlled Key) identified as the weakness type.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-45666 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-45666

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-45666 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45666

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.