CVE-2026-34226
High
Description
Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Versions prior to 20.8.9 may attach cookies from the current page origin (`window.location`) instead of the request target URL when `fetch(..., { credentials: "include" })` is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.
SeverityHigh
CVSS7.5
Exploit probability—
ProductCapricorn86 Happy Dom
PublishedMar 27, 2026
First seenMar 27, 2026
Weakness typeCWE-201CWE-201CWE-359CWE-359
How to fix
Update
- capricorn86 happy_dom20.8.9 or later
- happy-dom20.8.9 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| capricorn86 happy_dom | v < 20.8.9 | 20.8.9 |
| happy-domnpm | v < 20.8.9 | 20.8.9 |
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