CVE-2026-53666: React Router is a router for React

Q: How do I fix CVE-2026-53666?

react-router: upgrade to 7.18.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-53666 being exploited?

CVE-2026-53666 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-53666 affect?

CVE-2026-53666 affects react-router. Severity is medium (CVSS 6.1). 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

Q: How urgent is CVE-2026-53666?

Priority 30/100. No elevated risk signals yet.

Routine

MEDIUM 6.1UPGRADE

CVE-2026-53666 is a medium-severity flaw (CVSS 6.1) affecting react-router. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 65%)
CISA exploited list	No
Weakness	CWE-470
Published	2026-07-27
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc. · Vendor: shopify

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-27 22:17 UTCPublished CVE record published
2026-10-24 13:10 UTCUpdated Record last modified

shopify react-router UPGRADE

Affected: >= 6.4.0 and < 7.18.0

Fixed in: 7.18.0

Safe to downgrade to: a release before 6.4.0

1. Check installed version

npm ls react-router

2. UPGRADE to 7.18.0

npm install react-router@">=7.18.0"

3. If no update is available yet, DOWNGRADE to a release before 6.4.0

npm view react-router versions npm install react-router@"<6.4.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-53666?

react-router: upgrade to 7.18.0. Exact commands for each OS are on this page.

Is CVE-2026-53666 being exploited?

CVE-2026-53666 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-53666 affect?

CVE-2026-53666 affects react-router. Severity is medium (CVSS 6.1). 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

How urgent is CVE-2026-53666?

Priority 30/100. No elevated risk signals yet.

Software pages

React vulnerabilities · Shopify vulnerabilities

Related CVEs

CVE-2026-55685 HIGH 7.5 UPGRADE React Router is a router for React
CVE-2026-53667 MEDIUM 6.9 UPGRADE React Router is a router for React
CVE-2026-53668 MEDIUM 6.9 UPGRADE React Router is a router for React
CVE-2026-53669 MEDIUM 6.1 UPGRADE React Router is a router for React

References

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