Open WebUI: Stored cross-site scripting via citation embed_url
Summary
Open WebUI versions from 0.6.33 before 0.11.4 contain a stored cross-site scripting vulnerability in chat citations. An authenticated user can store a javascript: URL in a citation's embed_url field and share the chat. If another user clicks the citation, the URL is passed to window.open and the script runs in the Open WebUI origin, where it can read localStorage.token and act as that user, including administrators. Exploitation requires a valid account and a victim who clicks the crafted citation in a shared chat.
Affected
- Open WebUI 0.6.33 up to but not including 0.11.4 (default configuration)
Fixed in
- Upgrade to Open WebUI 0.11.4 or later (fixed by PR #29701)
Workaround
Unknown. No vendor workaround is documented because the fix is an upgrade.
Exploitation
- The advisory describes a proof of concept by the reporter.
- No known exploitation in the wild is reported.
- CISA SSVC: exploitation none, not automatable.
- EPSS is low.
Our recommendation
- Inventory all Open WebUI instances and their versions.
- Upgrade all instances in the affected range to 0.11.4 or later, ideally the current stable release.
- Prioritise instances that are internet-facing or have open registration.
- Restrict who can create accounts and share chats.
- Warn users not to click citations in untrusted shared chats until the upgrade is complete.
- Review administrator accounts for signs of misuse.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-qpqv-xwg8-cqpj github.com
- VulnCheck Advisory: Open WebUI Stored XSS via Citation embed_url www.vulncheck.com
- OSV: CVE-2026-109291 osv.dev
- OpenCVE: CVE-2026-109291 app.opencve.io
- HOL Guard: CVE-2026-109291 hol.org
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 10:54.
Original description (NVD)
Open WebUI from 0.6.33 before 0.11.4 contains a cross-site scripting vulnerability that allows authenticated users to execute script in victims' sessions by storing javascript: URLs in citation embed_url fields. Attackers can share a crafted chat whose citation, when clicked, is passed to window.open, letting them steal localStorage.token and act as the victim.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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