CVE-2026-42211
Description
A flaw was found in React Router when operating in Framework Mode. A remote attacker could exploit an existing prototype pollution vulnerability within the application code. This could lead to unauthorized remote code execution (RCE) on the server through a two-step attack involving external requests. This vulnerability poses a significant risk, potentially allowing an attacker to take control of the affected system.
Statement
An Important remote code execution flaw exists in React Router versions 7.0.0 through 7.14.1 when utilized in Framework Mode. This vulnerability requires an existing prototype pollution flaw within the application to enable a two-step attack, leading to unauthorized remote code execution on the server. Red Hat products employing React Router in Declarative Mode or Data Mode are not impacted.
Mitigation
To mitigate this vulnerability, ensure that applications using React Router are not configured in Framework Mode. Instead, utilize Declarative Mode (`<BrowserRouter>`) or Data Mode (`createBrowserRouter/<RouterProvider>`), as these modes are not susceptible to this flaw.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | N/A | 8.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data
An attacker could modify sensitive data or program variables.
Integrity
Technical Impact: Execute Unauthorized Code or Commands
Other,Integrity
Technical Impact: Varies by Context; Alter Execution Logic
Frequently Asked Questions
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