Critical 9.8Published Mar 27, 2026

CVE-2026-33943Happy DOM is a JavaScript implementation of a web browser without its graphical user interface.

Updated under an hour ago (2026-10-19 11:23 UTC)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for capricorn86 happy_dom

Exploited in the last 30 days

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. In versions 15.10.0 through 20.8.7, a code injection vulnerability in `ECMAScriptModuleCompiler` allows an attacker to achieve Remote Code Execution (RCE) by injecting arbitrary JavaScript expressions inside `export { }` declarations in ES module scripts processed by happy-dom. The compiler directly interpolates unsanitized content into generated code as an executable expression, and the quote filter does not strip backticks, allowing template literal-based payloads to bypass sanitization. Version 20.8.8 fixes the issue.

CVSS: 9.8 CRITICAL (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-94, CWE-917
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Modified
Record last updated: Jul 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

capricorn86 happy_dom capricorn86:happy_dom	from 15.10.0 before 20.8.8	NVD

References

https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3cpatch
https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8product, release-notes
https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64exploit, vendor-advisory
https://access.redhat.com/security/cve/CVE-2026-33943
https://bugzilla.redhat.com/show_bug.cgi?id=2452522
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.