Open WebUI: Open WebUI has stored XSS in Excel file preview
Open WebUI
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- Severity
- High, CVSS 8.7
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
- Record
- CVE-2026-44549
- Affects
- Open WebUI
- Known exploited
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- May 15, 2026
- Source last modified
- June 17, 2026
Description
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.8.0, Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger. This vulnerability is fixed in 0.8.0.
Description quoted from the NVD record.
Who is affected
Open WebUI is a chat program that your organization runs on its own computers to talk with AI language models, and it can work entirely offline. This flaw affects versions before 0.8.0. The problem is in the feature that shows a preview of Excel spreadsheet files attached in a chat. Someone can attach a specially crafted Excel file that hides harmful script code. When another person previews that file, the code runs in that person's web browser. This flaw is rated High.
What to do
- The person who installed or runs Open WebUI for your organization should check which version is in use.
- If the version is older than
0.8.0, update Open WebUI to0.8.0or a later release, which fixes this flaw. - If an IT provider or vendor runs Open WebUI for your organization, send them this advisory and ask when the update to
0.8.0will be done. - After the update, check that Open WebUI now shows version
0.8.0or later, so you know the fix is in place.
Analysis written from the source record as of June 17, 2026 and reviewed before publishing.