CVE-2026-45318 Open WebUI: Stored XSS via unsanitized Office/Excel/DOCX file preview rendering ({@html} without DOMPurify)
Attackers can execute arbitrary scripts in victim browsers by uploading malicious Office files, leading to potential account takeover.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-45318?
CVE-2026-45318 is a medium-severity cross-site scripting vulnerability in Openwebui Open Webui, published on 15 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.3, his advisory tracks a regression of the original Excel-preview XSS (CVE-2026-44549). The same root cause — XLSX.utils.sheet_to_html() output rendered via {@html excelHtml} without DOMPurify — was reintroduced sometime after v0.8.0 and is exploitable again This vulnerability is fixed in 0.9.3.
Weakness: CWE-79
Which versions are affected by CVE-2026-45318?
3 open source packages ship an affected version, including open-webui. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
open-webui PyPI | All versions | 0.9.3 |
open-webui PyPI | All versions | 0.9.3 |
open-webui PyPI | All versions | 0.9.3 |
Products include Openwebui Open Webui.
How do I fix CVE-2026-45318?
Upgrade open-webui to 0.9.3 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-45318 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45318 exists.
Other vulnerabilities in Openwebui Open Webui
- CVE-2026-44551 Open WebUI: LDAP Empty Password Authentication Bypass
- CVE-2026-56400 open-webui - Remote Code Execution via CORS Misconfiguration and Session Validation
- CVE-2024-8017 Cross-site Scripting (XSS) in open-webui/open-webui
- CVE-2026-45672 Open WebUI: Jupyter code execution works despite `ENABLE_CODE_EXECUTION=false` — feature gate bypassed
- CVE-2026-87995 Open WebUI: Same-origin XSS to account takeover via terminal port-preview iframe hardcoding allow-same-origin
Sources
Also known as GHSA-hcwp-82g6-8wxc, PYSEC-2026-2731.