---
id: CVE-2026-86644
title: A vulnerability was determined in star7th showdoc up to 3.9.1
summary: >-
  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 s…
severity: low
cvss: 3.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-79
  - CWE-94
vendor: star7th
product: showdoc
affected:
  - showdoc 3.9.0
  - showdoc 3.9.1
published: '2026-09-08'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T18:33:29.460'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86644'
references:
  - url: 'https://gist.github.com/saDL0w/36a72a076e9ab24408a3d27582e778b2'
    label: cna@vuldb.com
  - url: 'https://github.com/star7th/showdoc/'
    label: cna@vuldb.com
  - url: >-
      https://github.com/star7th/showdoc/commit/a8ea1520850b4242f395247f72e87e597506cef0
    label: cna@vuldb.com
  - url: 'https://github.com/star7th/showdoc/releases/tag/v3.9.2'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/cve/CVE-2026-86644'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/submit/906282'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/vuln/399755'
    label: cna@vuldb.com
  - url: 'https://vuldb.com/vuln/399755/cti'
    label: cna@vuldb.com
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T15:42:51.554304Z'
ingestedAt: '2026-09-08T15:33:26.985Z'
epss: 0.00343
epssPercentile: 0.27959
---

## Overview

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."

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.