Is CVE-2026-42342 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-42342 being exploited in the wild.

How severe is CVE-2026-42342?

High severity, with a CVSS score of 7.5, published 2 June 2026.

Which products and versions are affected?

@remix-run/server-runtime (npm) >= 2.10.0, = 2.10.0, < 2.17.5, 2.10.0 - 2.17.4.

Is there a fix for CVE-2026-42342?

Yes. @remix-run/server-runtime (npm): upgrade to 2.17.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-42342 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-42342?

Check whether you run @remix-run/server-runtime (npm) or Remix Server-Runtime at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-42342: Remix React Router DoS via unbounded path expansion in __manifest

Q: Is there a fix for CVE-2026-42342?

Yes. @remix-run/server-runtime (npm): upgrade to 2.17.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-42342 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-42342?

Check whether you run @remix-run/server-runtime (npm) or Remix Server-Runtime at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-42342 · Severity: high · CVSS 7.5 · Published 2026-06-02

React Router, a popular library for managing navigation in web applications, is vulnerable to a denial-of-service attack when used in Framework Mode. An attacker can send specially crafted requests to a specific internal endpoint that cause the server to consume excessive resources. This can lead to significant slowdowns or make the application completely unavailable to legitimate users.

Technologies: @remix-run/server-runtime (npm), Remix Server-Runtime. Vendors: npm, Remix.

Quick answers

Is CVE-2026-42342 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-42342 being exploited in the wild.
How severe is CVE-2026-42342?: High severity, with a CVSS score of 7.5, published 2 June 2026.
Which products and versions are affected?: @remix-run/server-runtime (npm) >= 2.10.0, < 2.17.5, SEMVER:introduced=2.10.0,fixed=2.17.5; Remix Server-Runtime >= 2.10.0, < 2.17.5, 2.10.0 - 2.17.4.
Is there a fix for CVE-2026-42342?: Yes. @remix-run/server-runtime (npm): upgrade to 2.17.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-42342 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-42342?: Check whether you run @remix-run/server-runtime (npm) or Remix Server-Runtime at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

@remix-run/server-runtime (npm): upgrade to 2.17.5 or later
```
npm install @remix-run/server-runtime@2.17.5
```

Technical details

A vulnerability exists in React Router Framework Mode (and Remix v2.10.0 - 2.17.4) where the __manifest endpoint is susceptible to unbounded path expansion. This is classified as CWE-400: Uncontrolled Resource Consumption. An unauthenticated remote attacker can craft network requests that trigger disproportionate resource usage on the server, leading to service degradation or a complete crash. The issue does not affect applications using Declarative Mode or Data Mode. Patches are available in React Router v7.15.0 and @remix-run/server-runtime v2.17.5.

Affected products

remix-run react-router >= 7.0.0, < 7.15.0
remix-run @remix-run/server-runtime >= 2.10.0, < 2.17.5

Identifiers

CVE-2026-42342
GHSA-8x6r-g9mw-2r78

Timeline

2026-06-02: disclosed
2026-06-03: advisory

References

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