CVE-2026-70493

Received Received - Intake

ReDoS Vulnerability in Open WebUI

Publication date: 2026-08-04

Last updated on: 2026-08-04

Assigner: GitHub, Inc.

Description

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.6 until 0.11.0, the built-in knowledge search path in backend/open_webui/tools/knowledge_fs.py and backend/open_webui/tools/builtin.py let a chat participant choose a pattern used to grep knowledge files. Patterns containing regex metacharacters were compiled with Python's backtracking re engine and run against every line of every reachable file with no time limit, so a crafted pattern such as (x|x)*y and one matching uploaded file line can pin one CPU core and block the event loop. This causes availability impact for every other user of the affected worker. This issue is fixed in 0.11.0.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-04

Last Modified

2026-08-04

Generated

2026-08-05

AI Q&A

2026-08-05

EPSS Evaluated

N/A

NVD

CVE-2026-70493

Affected Vendors & Products

Vendor	Product	Version / Range
open_webui	open_webui	to 0.11.0 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-1333	The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.

Attack-Flow Graph

Executive Summary

Open WebUI versions 0.9.6 to 0.11.0 contain a flaw in the knowledge search feature. A chat participant can craft a regex pattern with metacharacters that triggers Python's backtracking engine. When executed against files, this consumes excessive CPU resources, blocking the event loop and causing denial of service for other users.

Detection Guidance

Check Open WebUI version. If between 0.9.6 and 0.11.0, the system is vulnerable. Monitor for high CPU usage or blocked event loops during knowledge searches.

Impact Analysis

This vulnerability allows an attacker to disrupt service availability for all users on the affected Open WebUI instance. It can lead to system slowdowns or complete unresponsiveness, affecting legitimate users' ability to access the platform.

Mitigation Strategies

Upgrade Open WebUI to version 0.11.0 or later to patch the regex engine issue. Restrict user access to knowledge search features until patched.

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