CVE-2026-53666 MEDIUM

CVE-2026-53666: React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration

Vendor Remix-Run

Product react-router

Weakness CWE-470

Published July 27, 2026

Last update July 28, 2026

View on NVD All CVEs

CVSS base score

6.1/10

Attack vector Network

Attack complexity Low

Privileges required None

User interaction Required

Confidentiality Low

Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

What the vulnerability does

01Description

React Router is a router for React. In versions 6.4.0 through 7.17.0, if application code was written in a way that allows attacker-supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for an attacker to trigger unexpected constructor execution on the client, which would in turn trigger an outbound network request. This is only possible with very specific (and unlikely) application-layer code. Note that this does not impact an application if it is using Declarative Mode. It only impacts Framework Mode and Data Mode applications that perform manual SSR/hydration. This issue has been fixed in version 7.18.0.

Key dates

02Disclosure timeline

July 27, 2026 CVE published

July 28, 2026 Record updated

External resources

03References

NVD — National Vulnerability Database https://nvd.nist.gov/vuln/detail/CVE-2026-53666 CWE — Common Weakness Enumeration https://cwe.mitre.org/data/definitions/470.html AskarLabs — CWE-470 write-up Use of Externally-Controlled Input to Select Classes or Code (Unsafe Reflection)