CVE-2026-33943

Summary

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.

Affected Software

Weaknesses

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

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: no
  • Technical Impact: total

Additional References

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

happy-dom: Happy DOM: Remote Code Execution via JavaScript expression injection

Additional References

• 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

References

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

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