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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.

Official resources

2026-05-15