CVE-2026-33943
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.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 9.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.97%
- Percentil entre todas las CVEs puntuadas: 61
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access95 % - Impacto principal
T1059.007JavaScriptexecution90 %
Vulnerabilidad de inyección de código en Happy DOM (servidor/librería web expuesta en red), permitiendo RCE mediante inyección en módulos ES. El atacante ejecuta JavaScript arbitrario sin autenticación (PR:N, UI:N, AV:N).
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- CWE-94
- CWE-917
Referencias
- https://github.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3c
- https://github.com/capricorn86/happy-dom/releases/tag/v20.8.8
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64
- https://access.redhat.com/security/cve/CVE-2026-33943
- https://bugzilla.redhat.com/show_bug.cgi?id=2452522
- https://github.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json
JSON original (NVD)
Mostrar
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