Summary
React Router: Unauthenticated Denial of Service via Inefficient Route Matching
This is a follow up to https://github.com/remix-run/react-router/security/advisories/GHSA-8x6r-g9mw-2r78 that covers additional reported scenarios in which the manifest endpoint could be accessed via unauthenticated targeted requests that would put heavy load on the server and slow down response times.
[!NOTE]
This only impacts Framework Mode applications. This does not impact your application if you are using Declarative or Data Mode.
Impact
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-55685? CVE-2026-55685 is a high-severity uncontrolled resource consumption vulnerability in react-router (npm), affecting versions >= 7.0.0, < 7.18.0. It is fixed in 7.18.0. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- Which versions of react-router are affected by CVE-2026-55685? react-router (npm) versions >= 7.0.0, < 7.18.0 is affected.
- Is there a fix for CVE-2026-55685? Yes. CVE-2026-55685 is fixed in 7.18.0. Upgrade to this version or later.
- Is CVE-2026-55685 exploitable, and should I be worried? Whether CVE-2026-55685 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-55685 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-55685? Upgrade
react-routerto 7.18.0 or later.