CVE-2026-44549: Open WebUI: Stored XSS in excel file preview

Severity: high (CVSS 8.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-15 · updated 2026-06-17
Weakness: CWE-79

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.

Affected products

open-webui: before 0.8.0 — fixed in 0.8.0

How to fix

Upgrade to a fixed version: open-webui 0.8.0. Check the vendor advisory for mitigations.

References

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