GHSA-q6xv-jm4v-349h
Cross-site Scripting in ZenUML
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @zenuml/core | < 3.23.25 | 3.23.25 |
Details
As written in the advisory (Markdown source, shown as plain text).
### 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.
https://github.com/mermaid-js/zenuml-core/blob/dcfee8cde42673c09e19401f43ad8506658c8442/src/components/DiagramFrame/SeqDiagram/MessageLayer/Block/Statement/Comment/Comment.vue#L65
### 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.
References
External links from the advisory. They lead to third-party sites.