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CVE-2026-44564 open-webui CVE debrief

Open WebUI versions prior to 0.9.0 contain an authorization bypass vulnerability in the Socket.IO real-time collaboration subsystem. The ydoc:document:update event handler validates that a user is a member of a document's Socket.IO room but fails to verify write permissions. Users with read-only access can join document rooms via ydoc:document:join (which only requires read permission) and subsequently emit ydoc:document:update events that modify the in-memory Yjs document state. These unauthorized modifications are broadcast to all collaborators in real time, allowing read-only users to alter shared documents. The vulnerability stems from missing authorization checks between room membership validation and permission enforcement. This issue was fixed in version 0.9.0.

Vendor
open-webui
Product
Unknown
CVSS
MEDIUM 5.4
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 multi-user document collaboration features enabled, particularly those relying on read-only access controls for sensitive document sharing.

Technical summary

The vulnerability exists in the ydoc:document:update Socket.IO event handler (line 678) which checks room membership but not write permissions. The ydoc:document:join handler (line 520) allows read-only users to join document rooms. This architectural gap enables privilege escalation from read-only to write access for in-memory Yjs document state modifications.

Defensive priority

medium

Recommended defensive actions

  • Upgrade Open WebUI to version 0.9.0 or later to remediate the authorization bypass vulnerability
  • Review document collaboration permissions and audit access logs for unauthorized document modifications by read-only users
  • Implement additional authorization controls at the application layer to verify write permissions before processing Yjs document updates
  • Monitor Socket.IO event logs for anomalous ydoc:document:update emissions from users with read-only roles

Evidence notes

CVE published 2026-05-15; NVD analysis completed by 2026-05-19. Vendor advisory confirms exploitability and fix version. CVSS 5.4 (Medium) reflects network attack vector with low privileges required.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-44564 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-44564

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

  • CVE-2026-44564 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-44564

    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.