CVE-2026-45318Public exploitNetwork attack vector

Stored XSS via unsanitized Office preview HTML

Published May 15, 2026 · Updated May 15, 2026

Stored XSS in Open WebUI before 0.9.3 allows remote authenticated users to run script in another user's browser through a malicious Office file. The FilePreview.svelte and FileItemModal.svelte components render HTML converted from uploaded Office files without passing it through DOMPurify. An account is required to upload the document, and another user must preview it; successful execution exposes that viewer's session and accessible application data.

CVSS severity5.4
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Open WebUI before 0.9.3 allows remote authenticated users to run script in another user's browser through a malicious Office file. The FilePreview.svelte and FileItemModal.svelte components render HTML converted from uploaded Office files without passing it through DOMPurify. An account is required to upload the document, and another user must preview it; successful execution exposes that viewer's session and accessible application data.

The record

CVE
CVE-2026-45318
Published
May 15, 2026
Updated
May 15, 2026
Vendor
Open WebUI
Product
Open WebUI
Classifications
CWE-79, T1204.002, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 15, 2026CVE publishedPublication date reported by the CVE source.
  2. May 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.9.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Open WebUI · Open WebUIversion=< 0.9.3

Published CVSS scores

5.4GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.002User Execution: Malicious File
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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