Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') Affecting react-router package, versions >=6.4.0 <7.18.0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-JS-REACTROUTER-18313130
- published26 Jul 2026
- disclosed23 Jul 2026
- credityoyomiski
Introduced: 23 Jul 2026
NewCVE-2026-53666 (opens in a new tab)How to fix?
Upgrade react-router to version 7.18.0 or higher.
Overview
Affected versions of this package are vulnerable to Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') in the deserializeErrors function during SSR hydration. An attacker can cause unexpected constructor execution on the client, potentially resulting in outbound network traffic, by supplying crafted input that overwrites certain aspects of errors caught by the SSR process.
Note: This is only exploitable if the application is running in Framework Mode or Data Mode and performs manual SSR/hydration with code that allows attacker-controlled input to influence error deserialization.