CVE-2026-33943Public exploitNetwork attack vector

Remote code execution via interpolated export names

Published Mar 27, 2026 · Updated Mar 27, 2026

Code injection in Happy DOM 15.10.0 through 20.8.7 allows remote attackers to execute host commands through crafted ES module HTML. The ECMAScriptModuleCompiler export-object handler strips only quote characters from parsed export names and interpolates the remaining text as an executable expression. Execution requires attacker-controlled HTML to be processed with JavaScript evaluation enabled, granting the resulting process host privileges.

CVSS severity8.8
High
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in Happy DOM 15.10.0 through 20.8.7 allows remote attackers to execute host commands through crafted ES module HTML. The ECMAScriptModuleCompiler export-object handler strips only quote characters from parsed export names and interpolates the remaining text as an executable expression. Execution requires attacker-controlled HTML to be processed with JavaScript evaluation enabled, granting the resulting process host privileges.

The record

CVE
CVE-2026-33943
Published
Mar 27, 2026
Updated
Mar 27, 2026
Vendor
David Ortner
Product
Happy DOM
Classifications
CWE-94, CWE-917, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 15.10.0, < 20.8.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

David Ortner · Happy DOMversion=>= 15.10.0, < 20.8.8

Published CVSS scores

8.8Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
CWE-917Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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