Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-21884

Severity CVSS v4.0:
Pending analysis
Type:
CWE-79 Cross-Site Scripting (XSS)
Publication date:
10/01/2026
Last modified:
10/01/2026

Description

React Router is a router for React. In @remix-run/react version prior to 2.17.3. and react-router 7.0.0 through 7.11.0, a XSS vulnerability exists in in React Router's API in Framework Mode when using the getKey/storageKey props during Server-Side Rendering which could allow arbitrary JavaScript execution during SSR if untrusted content is used to generate the keys. There is no impact if server-side rendering in Framework Mode is disabled, or if Declarative Mode () or Data Mode (createBrowserRouter/) is being used. This issue has been patched in @remix-run/react version 2.17.3 and react-router version 7.12.0.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 8.20 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope (S): Changed
Confidentiality (C): High
Integrity (I): Low
Availability (A): None

Base Score 3.x
8.20
Severity 3.x
HIGH

References to Advisories, Solutions, and Tools