Vulnerability · Published Jul 27, 2026 · Assigned by GitHub_M

CVE-2026-55685React Router: Unauthenticated Denial of Service via Inefficient Route Matching

High 8.7

In plain English

A high-severity uncontrolled resource consumption in react-router from remix-run. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 54% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.7High

Exploit odds (30 days)0.7%top 46.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

React Router is a router for React. In versions 7.0.0 through 7.17.0, the manifest endpoint could be accessed via unauthenticated targeted requests that would put heavy load on the server and slow down response times. This issue is a follow up to CVE-2026-42342, and does not does not impact React Router applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>). This issue has been fixed in version 7.18.0.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	react-router	7.18.0	GHSA-chx6-hx7r-mcp5

Affected products (as reported)

Vendor	Product	Versions
remix-run	react-router	>= 7.0.0, < 7.18.0

Weakness: CWE-400, CWE-407 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

https://github.com/remix-run/react-router/security/advisories/GHSA-chx6-hx7r-mcp5 x_refsource_CONFIRM
https://github.com/remix-run/react-router/security/advisories/GHSA-8x6r-g9mw-2r78 x_refsource_MISC
https://github.com/remix-run/react-router/pull/15186 x_refsource_MISC
https://github.com/remix-run/react-router/commit/09e6020d1950e54f361f7ad00938ecd4dde60929 x_refsource_MISC
https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180 x_refsource_MISC
https://github.com/remix-run/react-router/releases/tag/react-router@7.18.0 x_refsource_MISC