CVE-2026-109299 open-webui CVE debrief

Who should care

Defenders responsible for Open WebUI instances, particularly those with automations permissions enabled, should assess exposure and prioritize verification and updates. This includes IT administrators, security teams, and operators who manage Open WebUI deployments. They should review the vulnerability details and take necessary actions to prevent potential denial of service. Additionally, defenders should consider the potential impact on system and user,

Why it matters

Defenders should care about CVE-2026-109299 because it allows authenticated users to stall Open WebUI instances, potentially impacting system availability and user productivity. Defenders responsible for Open WebUI instances, particularly those with automations permissions enabled, should assess exposure and prioritize verification and updates to prevent potential denial of service.

• Potential denial of service due to stalling of the instance
• Need for verification of Open WebUI version and automations permissions
• Possible impact on system availability and user productivity

Technical summary

The vulnerability allows authenticated users with automations permission to stall the instance by submitting unsatisfiable recurrence rules, which can cause the event loop to block for an extended period. This can lead to potential system downtime and impact on user productivity. The vulnerability is triggered by the server's inability to process invalid recurrence rules. The affected versions of Open WebUI are 0.9.0 before 0.11.4. Defenders should prioritize verifying and updating Open WebUI instances to version 0.11.4 or later.

Defensive priority

Defenders should prioritize verifying and updating Open WebUI instances to version 0.11.4 or later, and restrict automations permissions to trusted users.

Recommended defensive actions

• Verify and update Open WebUI instances to version 0.11.4 or later
• Restrict automations permissions to trusted users
• Monitor for suspicious activity on Open WebUI instances
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, including affected versions and a description of the denial of service vulnerability. The vulnerability was publicly disclosed on October 12, 2026, and there have been no changes to the CVE record since then. The source item and CVE record provide evidence of the vulnerability's existence and its potential impact on Open WebUI instances. However, additional verification is required to confirm the vulnerability's presence in specific deployments and to assess the risk

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.