RCE in Star7th Showdoc
CVE-2026-86644
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."
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.5 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (29.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 29.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Star7th Showdoc — versions 3.9.0, 3.9.1
Weakness classification (CWE)
References
- vuldb.com/vuln/399755 (vdb-entry)
- vuldb.com/vuln/399755/cti (signature, permissions-required)
- vuldb.com/cve/CVE-2026-86644 (third-party-advisory)
- vuldb.com/submit/906282 (third-party-advisory)
- gist.github.com/saDL0w/36a72a076e9ab24408a3d27582e778b2 (exploit)
- github.com/star7th/showdoc/commit/a8ea1520850b4242f395247f72e87e597506cef0 (patch)
- github.com/star7th/showdoc/releases/tag/v3.9.2 (patch)
- github.com/star7th/showdoc/ (product)
Frequently asked questions
- What is CVE-2026-86644?
- CVE-2026-86644 is a low-severity vulnerability in Star7th Showdoc, classified under Cross-site Scripting. CVSS score: 3.5/10. Published 2026-09-08.
- How severe is CVE-2026-86644?
- Low severity. CVSS v3 base score is 3.5 out of 10.