CVE-2026-45303

Description

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.5, through the HTML rendering view, scripts can be injected and executed. The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an iFrame with the allow-scripts allow-forms allow-same-origin sandbox directive. This means that the content is placed in a sandbox but with permission to execute scripts and access the parent’s data (e.g., local storage). As a result, only a few functions are restricted (e.g., displaying an alert box), but in effect, the sandbox attribute is largely nullified. This vulnerability is fixed in 0.6.5.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: HIGH
CVSS score: 7.7 / 10
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
Effective score: 7.7 / 10 HIGH source: CNA overview
CWE(s): CWE-79
Reserved: 2026-05-11
Published: 2026-05-15 23:21 UTC
Last updated: 2026-05-15 23:21 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/45xxx/CVE-2026-45303.json
Linked Threat: CVE-2026-45303 — Open WebUI: Stored XSS via the HTML renedering view

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-05-15 22:16:53 UTC
NVD last modified: 2026-05-19 14:16:45 UTC
NVD CVSS v3.1: 7.7 / 10 HIGH source: security-advisories@github.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
Exploitability subscore: 1.3 / 10
Impact subscore: 5.8 / 10
EPSS score: 0.0004 (probability of exploitation in next 30 days)
EPSS percentile: 10.88% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-30654
Assigner: GitHub_M
Published: May 15, 2026, 9:21:43 PM
Updated: May 19, 2026, 12:24:47 PM
EUVD base score (CVSS 3.1): 7.7 / 10
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
EUVD-reported EPSS: 0.0400
Vendors: open-webui
Products: open-webui (< 0.6.5)
Aliases: GHSA-4vrc-m9ch-6m3r

ENISA description: Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.5, through the HTML rendering view, scripts can be injected and executed. The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an iFrame with the allow-scripts allow-forms allow-same-origin sandbox directive. This means that the content is placed in a sandbox but with permission to execute scripts and access the parent’s data (e.g., local storage). As a result, only a few functions are restricted (e.g., displaying an alert box), but in effect, the sandbox attribute is largely nullified. This vulnerability is fixed in 0.6.5.

EUVD references (1)

https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3r

Affected products (1)

Vendor	Product	Versions	Platforms
open-webui	open-webui	`< 0.6.5` (affected)	—

Affected products — CPE 2.3 (1) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*

Vendor references (1)

References embedded in the original CVE record by the assigning CNA.

https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3r x_refsource_CONFIRM

MITRE references (1) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3r x_refsource_CONFIRM

Web references (3)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

https://nvd.nist.gov/vuln/detail/CVE-2026-45303 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-45303 tenable:www.cve.org
https://www.first.org/epss/ tenable:www.first.org

NVD-tagged references (2)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3r security-advisories@github.com ExploitMitigationVendor Advisory
https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3r 134c704f-9b21-4f2e-91b3-4a467353bcc0 ExploitMitigationVendor Advisory

Remediations (16)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

CISA Adds Six Known Exploited Vulnerabilities to Catalog

web:www.cisa.gov

Although BOD 22-01 only applies to FCEB agencies, CISA strongly urges all organizations to reduce their exposure to cyberattacks by prioritizing timely remediation of KEV Catalog vulnerabilities as part of their vulnerability management practice. CISA will continue to add vulnerabilities to the catalog that meet the specified criteria.

2026-05-22 17:24 UTC
April 2026 Third-Party Vulnerabilities and Patches | Recast

web:www.recastsoftware.com

This April was the most active month observed so far in terms of third‑party vulnerability disclosures and remediation activity. During the month, 360 unique vulnerabilities were identified across 96 applications, with vendors releasing 172 patched versions to address these issues. Compared to earlier months, April represents a clear peak in both vulnerability volume and patch output ...

2026-05-22 17:24 UTC
Critical Patches Issued for Microsoft Products, April 14, 2026

web:www.cisecurity.org

<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...

2026-05-22 17:24 UTC
Nvd - Cve-2026-45303

web:nvd.nist.gov

An official website of the United States government Here's how you know

2026-05-22 17:24 UTC
Emergency patch issued for Microsoft Office, 365 over hacking threat - MSN

web:www.msn.com

Original story: Microsoft has released an emergency patch for a vulnerability in the company's Office programs that's already being exploited by hackers.

2026-05-22 17:24 UTC
Patch Tuesday May 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-05-22 17:24 UTC
Microsoft's March 2026 update fixes 80+ security vulnerabilities

web:www.pcworld.com

This month's Patch Tuesday brings over 80 fixes for various security vulnerabilities. Fortunately, none are actively being exploited in the wild yet.

2026-05-22 04:01 UTC
Microsoft Patches 83 Vulnerabilities - SecurityWeek

web:www.securityweek.com

Microsoft has rolled out fixes for 83 vulnerabilities in its products, including a critical bug, but none of them require urgent attention.

2026-05-22 04:01 UTC
Patch Alert: Microsoft Fixes Nearly 80 Bugs, Including ... - TechRepublic

web:www.techrepublic.com

Microsoft's March Patch Tuesday fixes 78 vulnerabilities, including Office preview pane flaws, an Excel Copilot data leak risk, and an AI-discovered 9.8 severity bug.

2026-05-22 04:01 UTC
I tested Windows 11 March 2026 Updates: Everything new ... - Windows Latest

web:www.windowslatest.com

Windows 11 March 2026 Patch Tuesday update adds Emoji 16.0, Sysmon, network speed test, reliability improvements, and security fixes.

2026-05-22 04:01 UTC
March 2026 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft's March 2026 Patch Tuesday addresses 82 CVEs , featuring eight Critical vulnerabilities.

2026-05-22 04:01 UTC
Microsoft Patch Tuesday March 2026 - 78 Vulnerabilities Fixed ...

web:cybersecuritynews.com

Microsoft released its March 2026 Patch Tuesday security update on March 10, 2026 , addressing 78 vulnerabilities across Windows, Microsoft Office, Azure, SQL Server, and .NET. The update includes one actively exploited zero-day vulnerability and multiple Critical-rated flaws demanding immediate attention from security teams. The most urgent fix this month is CVE - 2026 -21262, the sole zero-day ...

2026-05-22 04:01 UTC
Nvd - Cve-2026-45301

web:nvd.nist.gov

An official website of the United States government Here's how you know

2026-05-22 04:01 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-22 04:01 UTC
Microsoft March 2026 Patch Tuesday fixes 2 zero-days, 79 flaws

web:www.bleepingcomputer.com

Today is Microsoft's March 2026 Patch Tuesday with security updates for 79 flaws, including 2 publicly disclosed zero-day vulnerabilities.

2026-05-22 04:01 UTC
Microsoft and Adobe Patch Tuesday, March 2026 Security Update Review

web:blog.qualys.com

Microsoft has rolled out its March 2026 Patch Tuesday updates, delivering a fresh batch of security fixes designed to keep Windows environments protected from emerging threats.

2026-05-22 04:01 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-45303.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "open-webui",
          "vendor": "open-webui",
          "versions": [
            {
              "status": "affected",
              "version": "< 0.6.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.5, through the HTML rendering view, scripts can be injected and executed. The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an iFrame with the allow-scripts allow-forms allow-same-origin sandbox directive. This means that the content is placed in a sandbox but with permission to execute scripts and access the parent\u2019s data (e.g., local storage). As a result, only a few functions are restricted (e.g., displaying an alert box), but in effect, the sandbox attribute is largely nullified. This vulnerability is fixed in 0.6.5."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.7,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-15T21:21:43.000Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3r",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-4vrc-m9ch-6m3r"
        }
      ],
      "source": {
        "advisory": "GHSA-4vrc-m9ch-6m3r",
        "discovery": "UNKNOWN"
      },
      "title": "Open WebUI: Stored XSS via the HTML renedering view"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-45303",
    "datePublished": "2026-05-15T21:21:43.000Z",
    "dateReserved": "2026-05-11T20:14:43.202Z",
    "dateUpdated": "2026-05-15T21:21:43.000Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}