CVE-2026-109300

MEDIUM 4.6

Open WebUI 0.6.31 before 0.11.4 Stored XSS via Tool-Call Embeds

CVSS Score

4.6

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-79
Vendor	open-webui
Product	open-webui
Published	Oct 12, 2026

Stay Ahead of the Next One

Get instant alerts for open-webui open-webui

Be the first to know when new medium vulnerabilities affecting open-webui open-webui are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

open-webui / open-webui

0.6.31 < 0.11.4

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

🔍 KadirArslan 🔍 5yu4n Classic298