Open WebUI: Stored cross-site scripting via DOCX preview
Summary
Open WebUI versions 0.11.1 up to 0.11.3 contain a stored cross-site scripting vulnerability in the DOCX preview component (DocxPreview.svelte). An authenticated user with upload rights can send a crafted DOCX attachment that runs script when another user previews it. If an administrator previews the file, the script can read the session token from local storage and take over the instance without a password. The attack requires the victim to open the attachment and switch to the Preview view.
Affected
- Open WebUI 0.11.1 up to, but not including, 0.11.4 (GHSA lists >= 0.11.1, <= 0.11.3)
- Default configuration is affected
Fixed in
- Open WebUI 0.11.4 (fix in pull request #29699)
Workaround
Unknown.
Exploitation
- CISA SSVC: exploitation status 'poc' (proof of concept available)
- Automatable: no
- Technical impact: total
- Reported with an end-to-end proof of concept for administrator takeover
Our recommendation
- Update Open WebUI to version 0.11.4 or later and check the official releases page for newer versions
- Until the update is done, limit DOCX uploads to trusted users and do not preview untrusted attachments, especially as an administrator
- Review the instance for unexpected administrator accounts, API keys and changed settings
- Check whether earlier DOCX/Excel preview issues (GHSA-hcwp-82g6-8wxc, fixed in 0.9.3) also apply to your version
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-f9xp-mfmq-x6cg github.com
- VulnCheck advisory: Open WebUI Stored XSS via DOCX Preview www.vulncheck.com
- OSV: CVE-2026-109290 osv.dev
- GitHub Security Advisory GHSA-hcwp-82g6-8wxc (earlier DOCX/Excel preview XSS) github.com
- Open WebUI v0.11.4 release github.com
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, 12:37.
Original description (NVD)
Open WebUI from 0.11.1 before 0.11.4 contains a stored cross-site scripting vulnerability in DocxPreview.svelte that allows authenticated users to execute script by uploading crafted DOCX attachments. Attackers can embed an OOXML altChunk HTML part or script-scheme hyperlink to steal a previewing administrator's session token from local storage and take over the instance.
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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.