GHSA-7rqq-prvp-x9jh — mermaid
Fix: mermaid-js/mermaid@5c69e5fGHSA-7rqq-prvp-x9jh is a Cross-site Scripting (XSS) vulnerability in mermaid. A fix is available for mermaid — see the affected versions and patch details below.
Mermaid improperly sanitizes sequence diagram labels leading to XSS
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-7rqq-prvp-x9jh.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
mermaidnpmDescription
Summary
In the default configuration of mermaid 11.9.0, user supplied input for sequence diagram labels is passed to innerHTML during calculation of element size, causing XSS.
Details
Sequence diagram node labels with KaTeX delimiters are passed through calculateMathMLDimensions. This method passes the full label to innerHTML which allows allows malicious users to inject arbitrary HTML and cause XSS when mermaid-js is used in it's default configuration (with KaTeX support enabled).
The vulnerability lies here:
export const calculateMathMLDimensions = async (text: string, config: MermaidConfig) => {
text = await renderKatex(text, config);
const divElem = document.createElement('div');
divElem.innerHTML = text; // XSS sink, text has not been sanitized.
divElem.id = 'katex-temp';
divElem.style.visibility = 'hidden';
divElem.style.position = 'absolute';
divElem.style.top = '0';
const body = document.querySelector('body');
body?.insertAdjacentElement('beforeend', divElem);
const dim = { width: divElem.clientWidth, height: divElem.clientHeight };
divElem.remove();
return dim;
};
The calculateMathMLDimensions method was introduced in 5c69e5fdb004a6d0a2abe97e23d26e223a059832 two years ago, which was released in Mermaid 10.9.0.
PoC
Render the following diagram and observe the modified DOM.
sequenceDiagram
participant A as Alice<img src="x" onerror="document.write(`xss on ${document.domain}`)">$$\\text{Alice}$$
A->>John: Hello John, how are you?
Alice-)John: See you later!
Impact
XSS on all sites that use mermaid and render user supplied diagrams without further sanitization.
Remediation
The value of the text argument for the calculateMathMLDimensions method needs to be sanitized before getting passed on to innerHTML.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | mermaid | ≥ 11.0.0-alpha.1&&< 11.10.0 | 11.10.0npm install mermaid@11.10.0 |
| 📦npm | mermaid | ≥ 10.9.0-rc.1&&< 10.9.4 | 10.9.4npm install mermaid@10.9.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mermaid, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mermaid to 11.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-7rqq-prvp-x9jh is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-7rqq-prvp-x9jh can be triaged on real exposure rather than presence alone.
Tailored to GHSA-7rqq-prvp-x9jh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-7rqq-prvp-x9jh in your dependencies?
O3 Security finds GHSA-7rqq-prvp-x9jh across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.