Happy-DOM has VM Context Escape

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No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Happy DOM v19 and lower contains a security vulnerability that puts the owner system at the risk of RCE (Remote Code Execution) attacks. A Node.js VM Context is not an isolated environment, and if the user runs untrusted JavaScript code within the Happy DOM VM Context, it may escape the VM and get access to process level functionality. It seems like what the attacker can get control over depends on if the process is using ESM or CommonJS. With CommonJS the attacker can get hold of the `require()` function to import modules. Happy DOM has JavaScript evaluation enabled by default. This may not be obvious to the consumer of Happy DOM and can potentially put the user at risk if untrusted code is executed within the environment. Version 20.0.0 patches the issue by changing JavaScript evaluation to be disabled by default.

Source published

10 Oct 2025 19:38:19 UTC

Source modified

10 Oct 2025 19:59:09 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 7.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:L/VI:H/VA:H/SC:H/SI:H/SA:H

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Happy DOM v19 and lower contains a security vulnerability that puts the owner system at the risk of RCE (Remote Code Execution) attacks. A Node.js VM Context is not an isolated environment, and if the user runs untrusted JavaScript code within the Happy DOM VM Context, it may escape the VM and get access to process level functionality. It seems like what the attacker can get control over depends on if the process is using ESM or CommonJS. With CommonJS the attacker can get hold of the `require()` function to import modules. Happy DOM has JavaScript evaluation enabled by default. This may not be obvious to the consumer of Happy DOM and can potentially put the user at risk if untrusted code is executed within the environment. Version 20.0.0 patches the issue by changing JavaScript evaluation to be disabled by default.

Source published

Oct 10, 2025, 7:38:19 PM (timezone not stated)

Source modified

Oct 10, 2025, 7:59:09 PM (timezone not stated)

Observed here

11 Nov 2026 04:29:52 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 7.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:L/VI:H/VA:H/SC:H/SI:H/SA:H

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Happy DOM v19 and lower contains a security vulnerability that puts the owner system at the risk of RCE (Remote Code Execution) attacks. A Node.js VM Context is not an isolated environment, and if the user runs untrusted JavaScript code within the Happy DOM VM Context, it may escape the VM and get access to process level functionality. It seems like what the attacker can get control over depends on if the process is using ESM or CommonJS. With CommonJS the attacker can get hold of the `require()` function to import modules. Happy DOM has JavaScript evaluation enabled by default. This may not be obvious to the consumer of Happy DOM and can potentially put the user at risk if untrusted code is executed within the environment. Version 20.0.0 patches the issue by changing JavaScript evaluation to be disabled by default.

Source published

10 Oct 2025 20:15:38 UTC

Source modified

8 Oct 2026 13:10:00 UTC

Observed here

25 Oct 2026 03:17:27 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 7.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:L/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

# Escape of VM Context gives access to process level functionality ## Summary Happy DOM v19 and lower contains a security vulnerability that puts the owner system at the risk of RCE (Remote Code Execution) attacks. A Node.js VM Context is not an isolated environment, and if the user runs untrusted JavaScript code within the Happy DOM VM Context, it may escape the VM and get access to process level functionality. It seems like what the attacker can get control over depends on if the process is using ESM or CommonJS. With CommonJS the attacker can get hold of the `require()` function to import modules. Happy DOM has JavaScript evaluation enabled by default. This may not be obvious to the consumer of Happy DOM and can potentially put the user at risk if untrusted code is executed within the environment. ## Reproduce ### CommonJS (Possible to get hold of require) ```javascript const { Window } = require('happy-dom'); const window = new Window({ console }); window.document.write(` <script> const process = this.constructor.constructor('return process')(); const require = process.mainModule.require; console.log('Files:', require('fs').readdirSync('.').slice(0,3)); </script> `); ``` ### ESM (Not possible to get hold of import or require) ```javascript const { Window } = require('happy-dom'); const window = new Window({ console }); window.document.write(` <script> const process = this.constructor.constructor('return process')(); console.log('PID:', process.pid); </script> `); ``` ## Potential Impact #### Server-Side Rendering (SSR) ```javascript const { Window } = require('happy-dom'); const window = new Window(); window.document.innerHTML = userControlledHTML; ``` #### Testing Frameworks Any test suite using Happy-DOM with untrusted content may be at risk ## Attack Scenarios 1. **Data Exfiltration**: Access to environment variables, configuration files, secrets 2. **Lateral Movement**: Network access for connecting to internal systems. Happy DOM already gives access to the network by fetch, but has protections in place (such as CORS and header validation etc.). 3. **Code Execution**: Child process access for running arbitrary commands 4. **Persistence**: File system access ## Recommended Immediate Actions 1. Update Happy DOM to v20 or above - This version has JavaScript evaluation disabled by default - This version will output a warning if JavaScript is enabled in an insecure environment 2. Run Node.js with the "--disallow-code-generation-from-strings" if you need JavaScript evaluation enabled - This makes sure that evaluation can't be used at process level to escape the VM - `eval()` and `Function()` can still be used within the Happy DOM VM without any known security risk - Happy DOM v20 and above will output a warning if this flag is not in use 4. If you can't update Happy DOM right now, it's recommended to disable JavaScript evaluation, unless you completely trust the content within the environment ## Technical Root Cause All classes and functions inherit from [Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function). By walking the constructor chain it's possible to get hold of [Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) at process level. As [Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) can evaluate code from strings, it's possible to execute code at process level. Running Node with the "--disallow-code-generation-from-strings" flag protects against this.

Source published

10 Oct 2025 23:46:42 UTC

Source modified

13 Oct 2025 15:48:53 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P

Publisher rating · CRITICAL