What is CVE-2026-33943?

CVE-2026-33943 is a high-severity vulnerability in Capricorn86 Happy-dom, classified under Code Injection. CVSS score: 8.8/10. Published 2026-03-27.

How severe is CVE-2026-33943?

High severity. CVSS v3 base score is 8.8 out of 10.

RCE in Capricorn86 Happy-dom

CVE-2026-33943

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 Exec…

Vulnerability class: RCE (Remote Code Execution)

EPSS: 0.001 (24.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

Capricorn86 Happy-dom — versions >= 15.10.0, < 20.8.8

Weakness classification (CWE)

CWE-94 — Code Injection

References

https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 (x_refsource_CONFIRM)
https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c (x_refsource_MISC)
https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-33943?: CVE-2026-33943 is a high-severity vulnerability in Capricorn86 Happy-dom, classified under Code Injection. CVSS score: 8.8/10. Published 2026-03-27.
How severe is CVE-2026-33943?: High severity. CVSS v3 base score is 8.8 out of 10.