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CVE-2026-42342: React Router is a router for React

37
Routine
HIGH 7.5REMOTEUPGRADEUPGRADE

CVE-2026-42342 is a high-severity flaw (CVSS 7.5) affecting react-router, remix-run\/server-runtime. 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 7.0.0 through 7.14.x of react-router and versions 2.10.0 through 2.17.4 of @remix-run/server-runtime, certain crafted requests can consume disproportionate server resources via unbounded path expansion in the __manifest endpoint, resulting in response time degradation and/or service unavailability for end users. This affects React Router Framework Mode applications as well as Remix applications. Thi

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.3% (top 78%)
CISA exploited listNo
WeaknessCWE-400
Published2026-06-02
Last modified2026-07-21
Publisher (CNA): GitHub, Inc. · Vendor: shopify

Share: LinkedIn · X · Reddit

Last updated 2026-07-21 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

shopify react-router UPGRADE
Affected: >= 7.0.0 and < 7.15.0
Fixed in: 7.15.0
Safe to downgrade to: a release before 7.0.0
1. Check installed version
npm ls react-router
2. UPGRADE to 7.15.0
npm install react-router@">=7.15.0"
3. If no update is available yet, DOWNGRADE to a release before 7.0.0
npm view react-router versions npm install react-router@"<7.0.0"
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.
shopify remix-run\/server-runtime UPGRADE
Affected: >= 2.10.0 and < 2.17.5
Fixed in: 2.17.5
Safe to downgrade to: a release before 2.10.0
1. Check installed version
npm ls remix-runserver-runtime
2. UPGRADE to 2.17.5
npm install remix-runserver-runtime@">=2.17.5"
3. If no update is available yet, DOWNGRADE to a release before 2.10.0
npm view remix-runserver-runtime versions npm install remix-runserver-runtime@"<2.10.0"
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-2026-42342?

react-router: upgrade to 7.15.0; remix-run\/server-runtime: upgrade to 2.17.5. Exact commands for each OS are on this page.

Is CVE-2026-42342 being exploited?

CVE-2026-42342 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-2026-42342 affect?

CVE-2026-42342 affects react-router, remix-run\/server-runtime. Severity is high (CVSS 7.5). React Router is a router for React. In versions 7.0.0 through 7.14.x of react-router and versions 2.10.0 through 2.17.4 of @remix-run/server-runtime, certain crafted requests can consume disproportionate server resources via unbounded path

How urgent is CVE-2026-42342?

Priority 37/100. High severity; Remotely exploitable, no login, no user action

Software pages

React vulnerabilities · Shopify vulnerabilities

Related CVEs

References

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