CVE-2026-86644 star7th showdoc API Page Save Endpoint editormd.js cross site scripting
Remote attackers can execute arbitrary scripts via the API Page Save Endpoint in showdoc, potentially leading to session hijacking or code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-86644?
CVE-2026-86644 is a medium-severity cross-site scripting vulnerability in star7th showdoc, published on 8 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
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."
Which versions are affected by CVE-2026-86644?
How do I fix CVE-2026-86644?
No fix has been published for CVE-2026-86644 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-86644 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86644 exists.
Sources
Also known as GHSA-rhvg-pc25-4r8p.