CVE-2026-26226 beautiful-mermaid < 0.1.3 SVG Attribute Injection
Attackers can inject malicious SVG attributes via Mermaid diagrams, leading to cross-site scripting and script execution in the embedding origin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-26226?
CVE-2026-26226 is a medium-severity cross-site scripting vulnerability in lukilabs beautiful-mermaid, published on 13 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
beautiful-mermaid versions prior to 0.1.3 contain an SVG attribute injection issue that can lead to cross-site scripting (XSS) when rendering attacker-controlled Mermaid diagrams. User-controlled values from Mermaid style and classDef directives are interpolated into SVG attribute values without proper escaping, allowing crafted input to break out of an attribute context and inject arbitrary SVG elements/attributes into the rendered output. When the generated SVG is embedded in a web page, this can result in script execution in the context of the embedding origin.
Weakness: CWE-79
Which versions are affected by CVE-2026-26226?
2 open source packages ship an affected version, including beautiful-mermaid.
| Package | Affected | Fixed in |
|---|---|---|
beautiful-mermaid npm | All versions | 0.1.3 |
beautiful-mermaid npm | All versions | 0.1.3 |
How do I fix CVE-2026-26226?
Upgrade beautiful-mermaid to 0.1.3 or later.
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-2026-26226 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-26226 exists.
Sources
Also known as GHSA-cgmm-x5ww-q5cr.