Cross-Site Scripting (XSS) in open-webui (CVE-2026-45318)
Summary
Cross-site scripting in open-webui (CVE-2026-45318). Risk of unauthorized operations or information disclosure. Exploitable via fileOfficeHtml. Mitigation: upgrade to 0.8.0 or later.
Original description
The description as published by the source.
Related advisory
This advisory tracks a regression of the original Excel-preview XSS that was
publicly disclosed and patched under GHSA-jwf8-pv5p-vhmc
(patched in v0.8.0). 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 as of v0.8.12 and through the version
range listed above. This advisory additionally covers the related
fileOfficeHtml sink in src/lib/components/chat/FileNav.svelte
(lines 458 and 1285) which was not part of the jwf8 advisory's scope.
Summary
Open WebUI renders user-uploaded Office files (Excel, DOCX) as HTML using Svelte's {@html} directive without DOMPurify sanitization. While the codebase has DOMPurify available and uses it in 9 out of 23 {@html} locations (39%), three file-preview rendering paths bypass it entirely, allowing Stored XSS when a user uploads a malicious document.
This is a classic defense propagation failure: the sanitization primitive exists in the codebase but is not consistently applied to all rendering surfaces.
Root Cause
The defense primitive exists: DOMPurify.sanitize() is imported and used in components like General.svelte, MarkdownInlineTokens.svelte, Banner.svelte, and SVGPanZoom.svelte.
But 3 file-preview paths skip it:
Occurrence 1: FilePreview.svelte — Office H…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-45318 has been found in open-webui.
Attackers can target a specific entry point like fileOfficeHtml over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade open-webui to 0.8.0 or later.
If unsure, ask your IT team or search "open-webui CVE-2026-45318" on the vendor's site.
CVE-2026-45318 (open-webui) — CWE-79 / CVSS v3 5.4
Attack vector: remote (network-reachable)
Attack surface: fileOfficeHtml / General.svelte / MarkdownInlineTokens.svelte / Banner.svelte
Patched: 0.8.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in open-webui. Attackers reach the vulnerable code path via fileOfficeHtml.
Check the vendor advisory for the affected versions of open-webui. Attack surface: fileOfficeHtml / General.svelte / MarkdownInlineTokens.svelte / Banner.svelte.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to 0.8.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'open-webui' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'open-webui' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
open-webuiを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade open-webui to 0.8.0ステージング環境で 0.8.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com