CVE-2026-109288: Open WebUI before 0.11.4 Stored XSS via javascript: URLs in Markdown Links

Severity: medium (CVSS 6.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-12 · updated 2026-10-13
Weakness: CWE-79

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.

Affected products

open-webui: before 0.11.4 — fixed in 0.11.4

How to fix

Upgrade to a fixed version: open-webui 0.11.4. Check the vendor advisory for mitigations.

References

https://github.com/open-webui/open-webui/security/advisories/GHSA-wf9m-46cp-c6h6
https://www.vulncheck.com/advisories/open-webui-before-0.11.4-stored-xss-via-javascript-urls-in-markdown-links
https://github.com/open-webui/open-webui/security/advisories/GHSA-wf9m-46cp-c6h6

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