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How the mentioned CVE works:
The vulnerability exists within React Router’s `meta()` and `` Framework Mode APIs during Server-Side Rendering (SSR). When these APIs generate a `script` tag with the type `ld+json` for structured data, they fail to properly sanitize or escape user-supplied input. An attacker can inject malicious JavaScript payloads into the untrusted content used to populate this script tag. During the SSR process, this unsanitized content is directly embedded into the HTML response sent to the client’s browser. The browser interprets the malicious payload within the script tag as executable code, leading to successful Cross-Site Scripting (XSS) attacks. This allows the attacker to execute arbitrary JavaScript in the context of the victim’s session, potentially compromising user data or taking over accounts. The vulnerability is specific to Framework Mode and does not affect Declarative or Data Router modes.
Platform: React Router
Version: Framework Mode
Vulnerability : XSS
Severity: Critical
date: 2026-01-08
Prediction: 2026-01-22
What Undercode Say:
curl -s “https://api.github.com/advisories?package=react-router”
grep -r “meta()” ./src –include=”.js”
npm audit –production
{
“vuln”: “CVE-2026-XXXX”,
“component”: “react-router/meta”
}
How Exploit:
POST /api/submit-json HTTP/1.1
Host: target.com
Content-Type: application/json
{“data”: ““}
Malicious JSON-LD injection.
Compromised user session.
Protection from this CVE:
Update React Router.
Sanitize all inputs.
Use Data Router.
Content Security Policy.
Impact:
Arbitrary JavaScript execution.
Session hijacking possible.
SSR applications compromised.
Data integrity loss.
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
