Log in Start free

Vulnerability · Published Oct 23, 2026 · Assigned by GitHub_M

CVE-2026-115895Happy DOM: Incomplete fix for CVE-2026-33943: unsanitized import alias leads to host code execution

High 8.8

In plain English

A high-severity code injection in happy-dom from capricorn86. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.5%top 58.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npmhappy-dom21.0.4GHSA-834v-8h66-3h79

Affected products (as reported)

VendorProductVersions
capricorn86 happy-dom >= 17.0.0, < 21.0.4

Weakness: CWE-94 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References