by Kastro
Paper/Archive/CVE-2026-33943

CVE-2026-33943

capricorn86 happy-dom — Happy DOM ECMAScriptModuleCompiler: unsanitized export names are interpolated as executable code

EPSS 0.6%public exploitCVSS 9.8
critical.is priorityof 100
50
CVSS 9.8 (NVD)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 50.9.509 × 2010.2Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
happy-dom>= 15.10.0, < 20.8.8–CNA
Red Hat Ansible Automation Platform 2see advisory–redhat-SADP
Red Hat OpenShift Container Platform 4see advisory–redhat-SADP

Scores by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub_M (CNA)8.8CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
redhat-SADP (CNA)8.8CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: total

References

exploitgithub.com/capricorn86/happy-dom/security/advisories/GHSA-6q6h-j7hj-3r64refgithub.com/capricorn86/happy-dom/commit/5437fdf8f13adb9590f9f52616d9f69c3ee8db3crefgithub.com/capricorn86/happy-dom/releases/tag/v20.8.8refaccess.redhat.com/security/cve/CVE-2026-33943refbugzilla.redhat.com/show_bug.cgi?id=2452522refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33943.json