CVE-2026-53666: CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') in remix-run react-router
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.
CVE-2026-53666: CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') in remix-run react-router
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.
CVSS v3.1
Score 6.1medium
Weaknesses
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-09T20:50:36.877Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a67cc2f9c2644c7f8dbb228
Added to database: 07/27/2026, 21:22:55 UTC
Last updated: 07/27/2026, 23:31:23 UTC
Views: 9
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