CVE-2026-109300CWE-79cross-site-scripting

CVE-2026-109300

Medium · published October 12, 2026

CVSS v3.1
4.6
EPSS
0%
Percentile
7.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
4.6 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
CVSS v4.0
5.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
EPSS
0.00179 · 7.1th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-10-12T21:17Z
References (3)
https://github.com/open-webui/open-webui/security/advisories/GHSA-9wj4-mcm3-ppj6 · [email protected]https://www.vulncheck.com/advisories/open-webui-0.6.31-before-0.11.4-stored-xss-via-tool-call-embeds · [email protected]https://github.com/open-webui/open-webui/security/advisories/GHSA-9wj4-mcm3-ppj6 · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 14 OCT 03:27Z
    EPSS moved — → 0%
    epss
  • 12 OCT 16:04Z
    Open WebUI 0.6.31 before 0.11.4 Stored XSS via Tool-Call Embeds
    cvelistv5
  • 12 OCT 16:04Z
    Open WebUI 0.6.31 before 0.11.4 Stored XSS via Tool-Call Embeds
    cvelistv5