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Medium · 6.1 CVE-2026-53666 EUVD-2026-49628GHSA-337j-9hxr-rhxg

React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration

Published Jul 27, 2026 · Updated Jul 28, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
remix-run react-router >= 6.4.0, < 7.18.0 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling keycloak-26.5 +1 26.5.7-r3 —
Wolfi rolling vitess-24 24.0.2-r7 —
Wolfi rolling vitess-24-compat 24.0.3-r7 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm react-router >= 6.4.0, < 7.18.0 7.18.0 GHSA-337j-9hxr-rhxg

References