CVE-2026-109288
Received Received - Intake

Stored XSS in Open WebUI via Unvalidated javascript: Links

Publication date: 2026-10-12

Last updated on: 2026-10-12

Assigner: VulnCheck

Description
Open WebUI before 0.11.4 contains a stored cross-site scripting vulnerability in MarkdownInlineTokens.svelte, which renders markdown link URLs into anchor hrefs without validating their scheme. Authenticated users can embed javascript: links in shared chats that, when clicked by a victim, steal the victim's JWT from local storage, including admins' tokens.

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Meta Information

Published
2026-10-12
Last Modified
2026-10-12
Generated
2026-10-12
AI Q&A
2026-10-12
EPSS Evaluated
N/A
NVD
CVE-2026-109288
EUVD
EUVD-2026-97590

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
open-webui open-webui 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This is a stored cross-site scripting (XSS) vulnerability in Open WebUI versions before 0.11.4. It allows authenticated users to embed malicious javascript: URLs in markdown links within shared chats. When victims click these links in certain browsers, the script executes, stealing their session token (JWT) from local storage, including admin tokens.

Detection Guidance

Check Open WebUI version with: curl -s http://<target>/api/version | grep version. If version is below 0.11.4, the system is vulnerable. Inspect shared chats for links starting with javascript: in markdown format. Review browser console logs for unauthorized script execution when clicking links.

Impact Analysis

An attacker could gain full access to your Open WebUI account by stealing your session token. If you are an admin, this could compromise the entire instance. The attack requires you to open a shared chat and click a malicious link in a vulnerable browser like Safari or Firefox.

Mitigation Strategies

Upgrade Open WebUI to version 0.11.4 or later immediately. Implement a Content-Security-Policy (CSP) header to block inline scripts if not already in place. Audit shared chats for malicious javascript: links and remove them. Restrict user permissions to minimize impact if tokens are compromised.

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