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MEDIUM

CVE-2026-53666

CVSS v3

6.1

MEDIUM

EPSS Score

0.4 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • react-routernpmfrom 6.4.0 · fixed in 7.18.0

Vendor advisories

  • CVE-2026-53666 Red Hat Product Security155 known affected

    react-router: React Router: Information disclosure via client-side constructor execution

    cryostat-openshift-console-plugin-npm as a component of Cryostat 4 · grafana-infinity-datasource-npm as a component of Cryostat 4 · react-router as a component of Cryostat 4

Full record on NVD

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.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Published
2026-07-27
Last Modified
2026-07-28

Frequently asked questions

What is CVE-2026-53666?

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.

Is CVE-2026-53666 actively exploited?

Active exploitation of CVE-2026-53666 has not been confirmed. Its EPSS score was 0.4% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-53666?

CVE-2026-53666 has a CVSS v3 base score of 6.1 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

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Same product first, then the same vendor advisory and the same publication week.

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