[ CVE-2026-115895 · Published 23 Oct 2026 ]
Happy DOM: Incomplete fix for CVE-2026-33943: unsanitized import alias leads to host code execution
[ Description ]Official 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.
[ Fixes ]Fixes and patches
- happy-dom 21.0.4Fixed version · GitHub Advisories · npm package happy-dom: upgrade to 21.0.4 or later (affected >= 17.0.0, <= 21.0.3)
[ Packages ]Affected open-source packages
- happy-dom npmAffected >= 17.0.0, <= 21.0.3 · fixed in 21.0.4 · GHSA-834v-8h66-3h79