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CVE-2026-86644 low CVSS 3.5

Cross-Site Scripting (XSS) in star7th showdoc (CVE-2026-86644)

Summary

Cross-site scripting in star7th showdoc (CVE-2026-86644). Risk of unauthorized operations or information disclosure. Exploitable via securityLevel.

Original description

The description as published by the source.

A vulnerability was determined in star7th showdoc up to 3.9.1. This vulnerability affects unknown code of the file web_src/public/editor.md/editormd.js of the component API Page Save Endpoint. Executing a manipulation can lead to cross site scripting. The attack may be launched remotely. The exploit has been publicly disclosed and may be utilized. Upgrading to version 3.9.2 is able to resolve this issue. This patch is called a8ea1520850b4242f395247f72e87e597506cef0. Upgrading the affected component is recommended. The vendor confirms: "The fix [...] sets Mermaid securityLevel to strict, disables htmlLabels, and sanitizes rendered SVG with DOMPurify."

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-2026-86644 has been found in star7th showdoc.
Attackers can target a specific entry point like securityLevel over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "star7th showdoc CVE-2026-86644" on the vendor's site.

CVE-2026-86644 (star7th showdoc) — CWE-79 / CVSS v3 3.5
Attack vector: remote (network-reachable)
Attack surface: securityLevel / strict / htmlLabels
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 star7th showdoc. Attackers reach the vulnerable code path via securityLevel.

📍 Affected scope

Check the vendor advisory for the affected versions of star7th showdoc. Attack surface: securityLevel / strict / htmlLabels.

🔥 Severity

Severity: Low (CVSS 3.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ 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. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで star7th showdoc を使っているサービスとバージョンを洗い出す。

  2. 2
    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。

References

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