CVE-2026-115895

Vulnerability Description

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. From 17.0.0 until 21.0.4, packages/happy-dom/src/module/ECMAScriptModuleCompiler.ts accepts a named ESM import alias without validating that it is a JavaScript binding identifier before inserting it into a generated destructuring binding. With enableJavaScriptEvaluation enabled, attacker-controlled HTML or module source can use an invalid alias that becomes a valid default initializer after compilation, causing the generated JavaScript to execute in the Node.js host process. The demonstrated reachable path uses a JSON module import attribute, which prevents the malicious alias from being emitted again in a later ESM circular-import assignment and keeps the generated function syntactically valid. This incomplete fix for CVE-2026-33943 is a distinct residual path because the earlier remediation validated the local export importName path but not the named-import alias. This issue is fixed in version 21.0.4.

CVSS Score

Related Weaknesses (CWE)

References

• https://github.com/capricorn86/happy-dom/commit/fd163520b74d9fa146be91f7b4e4f46d
• https://github.com/capricorn86/happy-dom/pull/2537
• https://github.com/capricorn86/happy-dom/releases/tag/v21.0.4
• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-834v-8h66-3h79
• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-834v-8h66-3h79