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CVE-2026-33943

8.8 · HIGH

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface.

Published Mar 27, 2026capricorn86CWE-94EPSS 0.65%

Overview

CVE-2026-33943 is a high-severity vulnerability affecting capricorn86 happy_dom. It was published on March 27, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories and patches from capricorn86. Update happy_dom to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus
capricorn86happy_dom>= 15.10.0, < 20.8.8Affected

References

GitHubgithub.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3cGitHubgithub.com/capricorn86/happy-dom/releases/tag/v20.8.8GitHubgithub.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64Refaccess.redhat.com/security/cve/CVE-2026-33943Refbugzilla.redhat.com/show_bug.cgi?id=2452522GitHubgithub.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-33943?

CVE-2026-33943 is a high-severity vulnerability affecting capricorn86 happy_dom. It was published on March 27, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-33943?

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-33943?

Check the references section for vendor advisories and patches from capricorn86. Update happy_dom to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-33943?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-33943 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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