SB2026042770 - Code Injection in Happy DOM

Description

This security bulletin contains information about 1 vulnerability.

1) Code Injection (CVE-ID: CVE-2026-33943)

CWE-ID: CWE-94 - Improper Control of Generation of Code ('Code Injection')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to execute arbitrary code.

The vulnerability exists due to improper control of code generation in ECMAScriptModuleCompiler when processing crafted ES module export declarations in HTML content. A remote attacker can inject a specially crafted JavaScript expression to execute arbitrary code.

Exploitation requires JavaScript evaluation to be enabled and user interaction to process attacker-controlled HTML content.

Remediation

Install update from vendor's website.

References

• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64
• https://github.com/advisories/GHSA-6q6h-j7hj-3r64