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CVE-2026-70486 high CVSS 8.2

Cross-Site Scripting (XSS) in open-webui (CVE-2026-70486)

Summary

Cross-site scripting in open-webui (CVE-2026-70486). Confidential information can be exposed externally. Exploitable via TERMINAL_SERVER_CONNECTIONS. Mitigation: upgrade to 0.11.0 or later.

Original description

The description as published by the source.

Summary

Any authenticated user with access to a terminal server could get script of their choosing to run in the Open WebUI origin itself. The HTML file preview rendered terminal-served files in an iframe whose sandbox always granted allow-same-origin alongside allow-scripts, and the file is served from a path on the application's own origin, so the sandbox provided no isolation at all. Script in a previewed file could read the victim's session token and take over the account.

Preconditions

  • At least one terminal server configured by an admin (TERMINAL_SERVER_CONNECTIONS, empty by default) and reachable by the victim. Deployments with no terminal server configured are not affected.
  • The attacker needs a normal authenticated account with access to that terminal server, no admin rights.
  • No victim interaction beyond having the chat open: a display_file tool call opens the preview automatically.
  • TERMINAL_PROXY_HEADERS unset, which is the default. An operator who had already set a restrictive Content-Security-Policy through it was not exposed, since those headers are merged into every proxied response including the served file.
  • The iframeSandboxAllowSameOrigin user setting is off by default, but the affected branch ignored it entirely.

Impact

The previewed document runs in the application origin, so it can reach the parent window, read the session token out of localStorage and exfiltrate it, which is full account takeover of the victim. If the vict…

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-2026-70486 has been found in open-webui.
Attackers can target a specific entry point like TERMINAL_SERVER_CONNECTIONS over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.2/10.
What to do: upgrade open-webui to 0.11.0 or later.
If unsure, ask your IT team or search "open-webui CVE-2026-70486" on the vendor's site.

CVE-2026-70486 (open-webui) — CWE-79 / CVSS v3 8.2
Attack vector: remote (network-reachable) / no user interaction
Attack surface: TERMINAL_SERVER_CONNECTIONS / display_file / TERMINAL_PROXY_HEADERS / iframeSandboxAllowSameOrigin
Patched: 0.11.0 — 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.

❓ What is the problem

Cross-site scripting (XSS) (CWE-79) exists in open-webui. Attackers reach the vulnerable code path via TERMINAL_SERVER_CONNECTIONS.

📍 Affected scope

Check the vendor advisory for the affected versions of open-webui. Attack surface: TERMINAL_SERVER_CONNECTIONS / display_file / TERMINAL_PROXY_HEADERS / iframeSandboxAllowSameOrigin.

🔥 Severity

Severity: High (CVSS 8.2/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 0.11.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

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

  1. 1
    Identify 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。

  2. 2
    Apply patch patch 
    Upgrade open-webui to 0.11.0

    ステージング環境で 0.11.0 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。

  3. 3
    Post-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

pip open-webui
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.11.0"}]}]
PyPI open-webui
[{"type":"ECOSYSTEM","events":[{"introduced":"0.9.0"},{"fixed":"0.11.0"}]}]

References

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