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CVE-2026-86062 medium CVSS 6.1

Cross-Site Scripting (XSS) in lightrag-hku (CVE-2026-86062)

Summary

Cross-site scripting in lightrag-hku (CVE-2026-86062). Risk of unauthorized operations or information disclosure. Exploitable via POST /documents/text. Mitigation: upgrade to 1.5.5 or later.

Original description

The description as published by the source.

Summary

The LightRAG WebUI renders assistant/answer chat content as raw HTML — react-markdown is
configured with rehypePlugins={[rehypeRaw]} and skipHtml={false} and no HTML sanitizer
(rehype-sanitize), element allow-list, or custom urlTransform. Because answer content is derived
from user-ingested documents, an attacker who can add a single document can store an HTML/JavaScript
payload that executes in the browser of any user who later retrieves it (typically an administrator),
leading to auth-token theft from localStorage and full API takeover. No authentication is required in
the default configuration.

Details

Sink — lightrag_webui/src/components/retrieval/ChatMessage.tsx:

  • Main answer (MessageMarkdown, lines ~348-351) and thinking content (lines ~252-272) render with
    rehypePlugins={[rehypeRaw, …]} and skipHtml={false}. The components map (lines ~111-156) only
    restyles safe formatting tags (p, h1–h4, ul, ol, li, code); there is no
    rehype-sanitize, no allowedElements/disallowedElements, and no custom urlTransform.
  • Second sink: mermaid is initialized with securityLevel: 'loose' (line ~433) and the rendered SVG is
    injected via container.innerHTML = svg (line ~483) + bindFunctions(container). 'loose' disables
    mermaid's output sanitization, so a ```mermaid block in answer content (HTML label / click
    directive) is an additional script-execution path.
  • Hardening (not code execution): KaTeX…

Source: NIST National Vulnerability Database 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-2026-86062 has been found in lightrag-hku.
Attackers can target a specific entry point like POST /documents/text over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.1/10.
What to do: upgrade lightrag-hku to 1.5.5 or later.
If unsure, ask your IT team or search "lightrag-hku CVE-2026-86062" on the vendor's site.

CVE-2026-86062 (lightrag-hku) — CWE-79 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: POST /documents/text / POST /documents/upload / POST /query / urlTransform
Patched: 1.5.5 — 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 lightrag-hku. Attackers reach the vulnerable code path via POST /documents/text without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of lightrag-hku. Attack surface: POST /documents/text / POST /documents/upload / POST /query / urlTransform.

🔥 Severity

Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 1.5.5.

🛡️ 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 POST /documents/text requests with malformed payloads or SQL meta-characters. Run grep -r 'lightrag-hku' . 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 'lightrag-hku' . | 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 lightrag-hku 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
    Hunt for indicators of compromise detect 
    grep 'POST /documents/text' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /documents/text への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Apply patch patch 
    Upgrade lightrag-hku to 1.5.5

    ステージング環境で 1.5.5 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と、Step 2 で見つけた異常検知の続報チェックを含めること。

  4. 4
    Post-deployment verification verify 
    Replay attack against POST /documents/text on staging to confirm patch closes the vector

    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 Step 2 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

pip lightrag-hku
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.5.5"}]}]

References

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