CVE-2026-109284 open-webui CVE debrief

Who should care

Defenders responsible for Open WebUI deployments, particularly those with shared folder configurations, should assess exposure and verify version 0.11.4 or later. This includes reviewing shared folder member permissions and ensuring that only authorized users have write access to shared folders. Additionally, defenders should monitor for suspicious chat fork activity and review compensating controls for exposed systems.

Why it matters

Defenders should care about CVE-2026-109284 because it allows shared folder members who have been downgraded to read-only to insert attacker-controlled chats into the source chat's folder, potentially affecting the folder owner and members. This vulnerability requires verification of Open WebUI version and shared folder member permissions, and may impact folder owners and members.

• Potential insertion of attacker-controlled chats into shared folders
• Possible visibility of attacker-controlled chats to folder owners and members
• Need for verification of Open WebUI version and shared folder member permissions
• Potential impact on folder owners and members due to improper authorization

Technical summary

The Open WebUI chat fork handler improperly authorizes shared folder members who have been downgraded to read-only, allowing them to insert attacker-controlled chats into the source chat's folder. This vulnerability requires verification of Open WebUI version and shared folder member permissions, and may impact folder owners and members due to improper authorization. The vulnerability is a result of inadequate access control in the chat fork handler, which allows read-only members to perform actions that could compromise the security of the shared folder.

Defensive priority

Defenders should prioritize verifying and upgrading to Open WebUI version 0.11.4 or later, and review shared folder member permissions.

Recommended defensive actions

• Verify Open WebUI version and upgrade to 0.11.4 or later
• Review shared folder member permissions
• Monitor for suspicious chat fork activity
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details on the improper authorization vulnerability in Open WebUI versions 0.11.0 before 0.11.4. The vulnerability was publicly disclosed on October 12, 2026, and there have been no changes to the CVE record since then. The source item provides additional context on the vulnerability, including its impact on shared folder members and the need for verification of Open WebUI version and permissions.

Sources and 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.