CVE-2026-53666

Medium

Description

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.

SeverityMedium
CVSS6.1
Exploit probability37. percentile0.4%
ProductShopify React-router
PublishedJul 27, 2026
First seenJul 27, 2026
Weakness typeCWE-470CWE-470

How to fix

Update
  • shopify react-router7.18.0 or later
  • react-router7.18.0 or later

Affected products

ProductAffected versionsFixed in
shopify react-router6.4.0 ≤ v < 7.18.07.18.0
react-routernpm6.4.0 ≤ v < 7.18.07.18.0

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