happy-dom 15.10.2/20.0.0/20.0.2 ECMAScriptModuleCompiler code injection

CVSS Meta Temp Score
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CTI Interest Score
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8.2$0-$5k0.00

Summaryinfo

A vulnerability was found in happy-dom. It has been rated as critical. This vulnerability affects unknown code of the component ECMAScriptModuleCompiler. Performing a manipulation results in code injection. This vulnerability is cataloged as CVE-2026-33943. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in happy-dom. This affects an unknown function of the component ECMAScriptModuleCompiler. The manipulation with an unknown input leads to a code injection vulnerability. CWE is classifying the issue as CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-33943. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1059 for this issue.

Upgrading to version 20.8.8 eliminates this vulnerability.

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Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.3
VulDB Meta Temp Score: 8.2

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

CNA Base Score: 8.8
CNA Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Code injection
CWE: CWE-94 / CWE-74 / CWE-707
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: happy-dom 20.8.8

Timelineinfo

03/27/2026 Advisory disclosed
03/27/2026 +0 days VulDB entry created
07/02/2026 +96 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-33943 (🔒)
GCVE (CVE): GCVE-0-2026-33943
GCVE (VulDB): GCVE-100-353829

Entryinfo

Created: 03/27/2026 07:34
Updated: 07/02/2026 01:56
Changes: 03/27/2026 07:34 (51), 07/02/2026 01:56 (21)
Complete: 🔍
Cache ID: 216::103

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