CVE-2026-109298: Open WebUI 0.11.0 before 0.11.4 Memory Exhaustion via Knowledge Search Regex

Q: Which deployments are exposed?

Open WebUI versions 0.11.0 through versions before 0.11.4 are affected. Exposure requires knowledge or chat file search functionality that permits user-chosen grep patterns.

Q: What access does an attacker need?

An attacker must be authenticated and able to cause the model to call the grep_knowledge_files tool. No user interaction beyond the attacker’s actions is required.

Q: What is the practical impact?

Short patterns containing nested counted repetition can trigger unbounded regex expansion during compilation. This can block the event loop and exhaust worker memory, causing a denial of service.

Q: How can I determine whether an instance may be under attack?

Look for authenticated use of grep_knowledge_files with short nested-repetition regex patterns, together with event-loop blocking or unusually high worker memory consumption. The compiled regex result is cached, which may allow memory consumption to persist after the triggering request.

Published Oct 12, 2026

Updated

Open WebUI 0.11.0 before 0.11.4 compiles user-chosen grep patterns for its knowledge and chat file search tools with a regex engine that expands nested counted repetition unbounded at compile time and caches the result. Authenticated users can have the model call grepknowledgefiles with short nested-repetition patterns, blocking the event loop and exhausting worker memory.

Affected Software

1 affected component

Open WebUI Open WebUI>=0.11.0<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

Which deployments are exposed?

Open WebUI versions 0.11.0 through versions before 0.11.4 are affected. Exposure requires knowledge or chat file search functionality that permits user-chosen grep patterns.

What access does an attacker need?

An attacker must be authenticated and able to cause the model to call the grep_knowledge_files tool. No user interaction beyond the attacker’s actions is required.

What is the practical impact?

Short patterns containing nested counted repetition can trigger unbounded regex expansion during compilation. This can block the event loop and exhaust worker memory, causing a denial of service.

How can I determine whether an instance may be under attack?

Look for authenticated use of grep_knowledge_files with short nested-repetition regex patterns, together with event-loop blocking or unusually high worker memory consumption. The compiled regex result is cached, which may allow memory consumption to persist after the triggering request.

CVE-2026-109298: Open WebUI 0.11.0 before 0.11.4 Memory Exhaustion via Knowledge Search Regex

Affected Software

Event History

Frequently Asked Questions

Which deployments are exposed?

What access does an attacker need?

What is the practical impact?

How can I determine whether an instance may be under attack?

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Resources

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Frequently Asked Questions

Which deployments are exposed?

What access does an attacker need?

What is the practical impact?

How can I determine whether an instance may be under attack?