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.
Blast Radius
@zenuml/coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
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 | 3.23.25 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @zenuml/core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @zenuml/core to 3.23.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q6xv-jm4v-349h 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 pinpoints whether GHSA-q6xv-jm4v-349h is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-q6xv-jm4v-349h. 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-q6xv-jm4v-349h in your dependencies?
O3 detects GHSA-q6xv-jm4v-349h across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.