High 8.8Published Oct 23, 2026

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

Updated under an hour ago (Oct 28, 2026, 8:50 AM ET)

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It affects capricorn86 happy-dom. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.37%, higher than 30% of scored CVEs.

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Every CVE for capricorn86 happy-dom

Exploited in the last 30 days

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: 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-94
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.37% (percentile 30)
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Oct 23, 2026
First seen by InfoSec Signals: Oct 23, 2026

Affected products

Affected products

capricorn86 happy-dom capricorn86:happy_dom (from the name)	from 17.0.0, < 21.0.4	CNA record

References

References

https://github.com/capricorn86/happy-dom/security/advisories/GHSA-834v-8h66-3h79	x-refsource-confirm
https://github.com/capricorn86/happy-dom/pull/2537	x-refsource-misc
https://github.com/capricorn86/happy-dom/commit/fd163520b74d9fa146be91f7b4e4f46d6cccbe13	x-refsource-misc
https://github.com/capricorn86/happy-dom/releases/tag/v21.0.4	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.