vulnerability / NVI-00008973 / Revision 3
Happy DOM: SSRF via iframe and link stylesheet when parsing untrusted HTML
GitHub lists this reviewed advisory for happy-dom. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
8.6 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
8.6 HIGH (3.1)
security-advisories@github.com severity; no combined Null risk score.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
happy-dom
source listed<= 20.14.6
## Summary happy-dom v20.8.9 makes real server-side HTTP requests to arbitrary URLs when parsing HTML containing `` or `` elements. This behavior is enabled by default (`disableIframePageLoading: false`, `disableCSSFileLoading: false`). When an application uses happy-dom to parse untrusted HTML on the server side, an attacker can trigger Server-Side Request Forgery by embedding these elements. ## Affected Versions - happy-dom ` stylesheets fetch their `href` URL via real HTTP requests When untrusted HTML is parsed, these elements trigger real server-side HTTP requests to whatever URLs are specified. No special configuration or opt-in is needed. ## Proof of Concept ### Verified test (attacker server receives requests): ```javascript const http = require('http'); const { Window } = require('happy-dom'); // Start attacker server const srv = http.createServer((req, res) => { console.log(`SSRF HIT: ${req.method} ${req.url}`); res.writeHead(200
happy-dom
source listedSEMVER: introduced 0; fixed 21.0.0
## Summary happy-dom v20.8.9 makes real server-side HTTP requests to arbitrary URLs when parsing HTML containing `` or `` elements. This behavior is enabled by default (`disableIframePageLoading: false`, `disableCSSFileLoading: false`). When an application uses happy-dom to parse untrusted HTML on the server side, an attacker can trigger Server-Side Request Forgery by embedding these elements. ## Affected Versions - happy-dom ` stylesheets fetch their `href` URL via real HTTP requests When untrusted HTML is parsed, these elements trigger real server-side HTTP requests to whatever URLs are specified. No special configuration or opt-in is needed. ## Proof of Concept ### Verified test (attacker server receives requests): ```javascript const http = require('http'); const { Window } = require('happy-dom'); // Start attacker server const srv = http.createServer((req, res) => { console.log(`SSRF HIT: ${req.method} ${req.url}`); res.writeHead(200
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. NIST National Vulnerability Database
- vendor patch
The original advisory lists fixed boundaries 21.0.0 for happy-dom. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-c8p4-j97h-3vg8 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- GHSA-c8p4-j97h-3vg8 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2026-118660 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.