CVE-2024-38527 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in @zenuml/core. A fix is available for @zenuml/core — see the affected versions and patch details below.
Cross-site Scripting in ZenUML
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.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-38527.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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.
@zenuml/corenpmDescription
Summary
Markdown-based comments in the ZenUML diagram syntax are susceptible to Cross-site Scripting (XSS).
Details
The comment feature allows the user to attach small notes for reference. This feature allows the user to enter in their comment in markdown comment, allowing them to use common markdown features, such as ** for bolded text. However, the markdown text is currently not sanitized before rendering, allowing an attacker to enter a malicious payload for the comment which leads to XSS.
PoC
// p<img onerror=alert(1) src=""/>
A->B:hi
Above is a POC diagram payload that results in an XSS.
Here is a similar POC in mermaid.live: https://mermaid.live/edit#pako:eNpNjrFuwyAQhl8F3dRK1DaQGhs1kVq1Y6duFQsylwTVgEWw1MTyuxc5S7df39399y0wRIug4IZh9qMOdU2mF-dPJAZMKaa9GTHlB_ZILmnYa9BQH3R4fTq8qbMDCh6TN86WhkUHQjTkM3rUoEq0Jv2Ui7CWPTPn-HUNA6icZqQwT9ZkfHfmlIwHdTTjpVC0Lsf0eVfazChMJoBa4BdUL6uGC8n7TrCGd5zCFRRnXbVjvBVNK3gJXbtSuMVYSlnFC-Kyf961UshWbmXf2-y_xcf29c7WP2yrVC0
Impact
This puts existing applications that use ZenUML unsandboxed at risk of arbitrary JavaScript execution when rendering user-controlled diagrams.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @zenuml/core | all versions | 3.23.25npm install @zenuml/core@3.23.25 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @zenuml/core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @zenuml/core to 3.23.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-38527 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2024-38527 in your dependencies?
Find it across npm, including transitive dependencies.