CVE-2026-109297: Open WebUI 0.11.0 before 0.11.4 Denial of Service via Automation Recurrence Rules

Q: Who can exploit this issue?

An authenticated user who is permitted to create automations can submit a crafted recurrence rule. The attack is network-accessible and does not require user interaction.

Q: Which deployments are affected?

Open WebUI versions from 0.11.0 before 0.11.4 are affected. Exposure depends on whether users have permission to create automations.

Q: What is the operational impact of a successful attack?

A crafted rule can expand per second synchronously and block the shared event loop for minutes per request. The same rule can trigger the condition again on every scheduler poll, causing denial of service.

Q: Are there version-specific rule formats that can trigger the issue?

Whitespace-folded rules can bypass the validator across the affected range. In version 0.11.0, lowercase frequency values or rules with omitted RRULE prefixes can also trigger the issue.

Q: What can be done before upgrading?

Restrict automation-creation permission to trusted users and review existing automations for suspicious recurrence rules. This reduces the ability to submit or retain rules that cause per-second synchronous expansion.

Published Oct 12, 2026

Updated

Open WebUI 0.11.0 before 0.11.4 contains a denial of service vulnerability in the automation recurrence-rule validator, whose sub-daily frequency guard parses rule text more strictly than the calendar library that executes it. Users permitted to create automations can submit whitespace-folded rules (or, in 0.11.0, lowercase frequencies or omitted RRULE prefixes) that expand per-second synchronously, blocking the shared event loop for minutes per request and on every scheduler poll.

Affected Software

1 affected component

Open WebUI Open WebUI>=0.11.0<0.11.4

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade Open WebUI to a version that resolves this vulnerability.
Fixed in 0.11.4

Event History

Oct 12, 2026

CVE Published

via MITRE·04:04 PM

Data Sourced

via MITRE·04:04 PM

DescriptionSeverityWeakness

Data Sourced

via NVD·05:17 PM

DescriptionSeverityWeakness

Frequently Asked Questions

Who can exploit this issue?

An authenticated user who is permitted to create automations can submit a crafted recurrence rule. The attack is network-accessible and does not require user interaction.

Which deployments are affected?

Open WebUI versions from 0.11.0 before 0.11.4 are affected. Exposure depends on whether users have permission to create automations.

What is the operational impact of a successful attack?

A crafted rule can expand per second synchronously and block the shared event loop for minutes per request. The same rule can trigger the condition again on every scheduler poll, causing denial of service.

Are there version-specific rule formats that can trigger the issue?

Whitespace-folded rules can bypass the validator across the affected range. In version 0.11.0, lowercase frequency values or rules with omitted RRULE prefixes can also trigger the issue.

What can be done before upgrading?

Restrict automation-creation permission to trusted users and review existing automations for suspicious recurrence rules. This reduces the ability to submit or retain rules that cause per-second synchronous expansion.

CVE-2026-109297: Open WebUI 0.11.0 before 0.11.4 Denial of Service via Automation Recurrence Rules

Affected Software

Remediation

Event History

Frequently Asked Questions

Who can exploit this issue?

Which deployments are affected?

What is the operational impact of a successful attack?

Are there version-specific rule formats that can trigger the issue?

What can be done before upgrading?

Company

Resources

Contact

Frequently Asked Questions

Who can exploit this issue?

Which deployments are affected?

What is the operational impact of a successful attack?

Are there version-specific rule formats that can trigger the issue?

What can be done before upgrading?