CVE-2026-33943 Details
Description
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.
A remote code execution vulnerability has been identified in Happy DOM versions 15.10.0 prior to 20.8.7. The issue arises in the ECMAScript Module Compiler, where unsanitized export names in 'export { }' declarations are interpolated as executable code. This vulnerability allows an attacker to inject arbitrary JavaScript that is executed, potentially leading to unauthorized command execution on the host system. The flaw is exploitable when JavaScript evaluation is enabled, either by default or through user action.
Users can upgrade to Happy DOM version 20.8.8 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Mar 27, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2026-33943 | redhat-SADP | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2452522 | redhat-SADP | |
| https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json | redhat-SADP | |
| https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 | CISA-ADP | ExploitVendor Advisory |
| https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c | [email protected] | Patch |
| https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8 | [email protected] | ProductRelease Notes |
| https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64 | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-917 | Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection') | redhat-SADP |
| CWE-94 | Improper Control of Generation of Code ('Code Injection') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| capricorn86 happy dom | >= 15.10.0, < 20.8.8 |
CPE
Remediation
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Change History
7 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 15, 2026 | CVE Modified | redhat-SADP |
| Jun 30, 2026 | CVE Modified | redhat-SADP |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 13, 2026 | Initial Analysis | [email protected] |
| Mar 27, 2026 | CVE Modified | CISA-ADP |
| Mar 27, 2026 | New CVE Received | [email protected] |