CVE-2026-23630 Docmost is vulnerable to stored Cross-Site Scripting (XSS) through Mermaid rendering
Attackers can execute arbitrary JavaScript in victim browsers via malicious Mermaid diagrams in Docmost, potentially leading to account takeover.
- 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-2026-23630?
CVE-2026-23630 is a medium-severity cross-site scripting vulnerability in docmost, published on 21 Jan 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
Docmost is open-source collaborative wiki and documentation software. In versions 0.3.0 through 0.23.2, Mermaid code block rendering is vulnerable to stored Cross-Site Scripting (XSS). The frontend can render attacker-controlled Mermaid diagrams using mermaid.render(), then inject the returned SVG/HTML into the DOM via dangerouslySetInnerHTML without sanitization. Mermaid per-diagram %%{init}%% directives allow overriding securityLevel and enabling htmlLabels, permitting arbitrary HTML/JS execution for any viewer. This issue has been fixed in version 0.24.0.
Which versions are affected by CVE-2026-23630?
It affects 1 product.
Products include Docmost Docmost.
How do I fix CVE-2026-23630?
No fix has been published for CVE-2026-23630 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-2026-23630 being exploited?
There is no known exploitation of CVE-2026-23630 in the wild and no public exploit code.
Other vulnerabilities in docmost
- CVE-2026-24045 Docmost Affected by Stored XSS in Public Share Page
- CVE-2026-22249 Docmost affected by an Arbitrary File Write via Zip Import Feature (ZipSlip)
- CVE-2025-55574 Cross-site scripting in n/a
- CVE-2026-40927 Docmost: XSS in Comments with JavaScript URI
- CVE-2026-34212 Docmost page content has stored XSS via unsanitized attachment URLs
Sources
Also known as GHSA-r4hj-mc62-jmwj.