CVE-2026-88002

Analyzed Analyzed - Analysis Complete

Denial of Service in Open WebUI via Message Chain

Publication date: 2026-09-09

Last updated on: 2026-09-14

Assigner: GitHub, Inc.

Description

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.5.0 until 0.11.1, the message-chain reconstruction helper in backend/open_webui/utils/misc.py advanced through a chat history by map key but tracked visited entries using each message body's optional id field. An authenticated user could store id-less messages in a parent cycle and trigger a non-terminating walk that blocked the async event loop, grew memory until termination, and remained persistent across process restarts. This issue is fixed in version 0.11.1.

CVSS Scores

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Meta Information

Published

2026-09-09

Last Modified

2026-09-14

Generated

2026-09-30

AI Q&A

2026-09-10

EPSS Evaluated

2026-09-29

NVD

CVE-2026-88002

Affected Vendors & Products

Vendor	Product	Version / Range
openwebui	open_webui	From 0.5.0 (inc) to 0.11.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-835	The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

Attack-Flow Graph

Executive Summary

This vulnerability affects Open WebUI versions 0.5.0 to 0.11.0. It involves a flaw in message-chain reconstruction where the system tracks visited messages by their optional ID field but iterates through chat history using map keys. An attacker can create a cycle of messages without IDs, causing the system to enter an infinite loop while processing the chat history. This blocks the async event loop, consumes excessive memory until the process terminates, and persists even after restarting the process.

Detection Guidance

This vulnerability is specific to Open WebUI versions 0.5.0 to 0.11.0 and involves a denial-of-service condition caused by maliciously crafted message chains. Detection requires checking the installed Open WebUI version and monitoring for unusual memory usage or process hangs.

Impact Analysis

If exploited, this vulnerability can cause system slowdowns or complete unresponsiveness due to the blocked event loop and high memory usage. It may lead to denial-of-service conditions, preventing legitimate users from accessing the AI platform. Persistent memory growth could also degrade system performance over time.

Compliance Impact

The vulnerability could lead to denial-of-service (DoS) conditions by consuming excessive system resources, potentially disrupting availability of services. This may impact compliance with GDPR (availability principle) and HIPAA (access control and integrity requirements) if critical systems become unavailable or data integrity is compromised due to resource exhaustion.

Mitigation Strategies

Upgrade Open WebUI to version 0.11.1 or later immediately. If upgrading is not possible, restrict access to authenticated users only and monitor for suspicious message patterns that could trigger the vulnerability.

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