CVE-2026-109300

MEDIUMCVSS 4.6

Description

Open WebUI from 0.6.31 before 0.11.4 contains a stored cross-site scripting vulnerability in its Markdown renderer, which treats user-authored tool-call details blocks as tool output and mounts their embeds attribute in script-enabled iframes. Authenticated users can post crafted channel messages, chat messages, or citation content that runs JavaScript in viewers' browsers, enabling in-app phishing, or session hijacking where iframeSandboxAllowSameOrigin is enabled.

Timeline

Published:October 12th, 2026 5:17 PM

Last modified:October 15th, 2026 3:55 PM

CVSS Scoring

CVSS v3: 4.6 (MEDIUM)

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Weaknesses (CWE)

CWE-79

References & Reports

Advisories, patches, and third-party reports

https://github.com/open-webui/open-webui/security/advisories/GHSA-9wj4-mcm3-ppj6
https://www.vulncheck.com/advisories/open-webui-0.6.31-before-0.11.4-stored-xss-via-tool-call-embeds
https://github.com/open-webui/open-webui/security/advisories/GHSA-9wj4-mcm3-ppj6

Source: NIST NVD · Data may lag official sources by up to one minute