CVE-2026-53666
React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration
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.
INFO
Published Date :
July 27, 2026, 10:17 p.m.
Last Modified :
Oct. 24, 2026, 1:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Update React Router to version 7.18.0 or later.
- Review application code for SSR error handling.
- Ensure Declarative Mode is used if possible.
- Avoid manual SSR/hydration in Framework/Data Modes.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-53666.
| URL | Resource |
|---|---|
| https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180 | Release Notes |
| https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a | Patch |
| https://github.com/remix-run/react-router/pull/15175 | Issue Tracking Patch |
| https://github.com/remix-run/react-router/releases/tag/[email protected] | Release Notes |
| https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg | Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-53666 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-53666
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-53666 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-53666 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 24, 2026
Action Type Old Value New Value Added Translation Title: react-router de remix-run, Description: React Router es un router para React. En las versiones 6.4.0 a 7.17.0, si el código de la aplicación fue escrito de una manera que permite que la entrada suministrada por el atacante sobrescriba ciertos aspectos de errores capturados por el proceso SSR, entonces era posible para un atacante desencadenar la ejecución inesperada del constructor en el cliente, lo que a su vez desencadenaría una solicitud de red saliente. Esto solo es posible con código de capa de aplicación muy específico (e improbable). Tenga en cuenta que esto no impacta una aplicación si está utilizando el Modo Declarativo. Solo impacta las aplicaciones de Modo Framework y Modo de Datos que realizan SSR/hidratación manual. Este problema ha sido solucionado en la versión 7.18.0. -
Initial Analysis by [email protected]
Aug. 03, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:shopify:react-router:*:*:*:*:*:node.js:*:* versions from (including) 6.4.0 up to (excluding) 7.18.0 Added Reference Type GitHub, Inc.: https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a Types: Patch Added Reference Type GitHub, Inc.: https://github.com/remix-run/react-router/pull/15175 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/remix-run/react-router/releases/tag/[email protected] Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg Types: Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 28, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-53666', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-28T15:09:52.899776Z'} -
New CVE Received by [email protected]
Jul. 27, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'remix-run', 'product': 'react-router', 'versions': [{'status': 'affected', 'version': '>= 6.4.0, < 7.18.0'}]}] Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Added CWE CWE-470 Added Reference https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180 Added Reference https://github.com/remix-run/react-router/commit/9d22943fd46c8ae4b08236425fa3549e10e9ad1a Added Reference https://github.com/remix-run/react-router/pull/15175 Added Reference https://github.com/remix-run/react-router/releases/tag/[email protected] Added Reference https://github.com/remix-run/react-router/security/advisories/GHSA-337j-9hxr-rhxg