High severity · published Jul 27, 2026
CVE-2026-55685
React Router: Unauthenticated Denial of Service via Inefficient Route Matching
7.5
CVSS
0.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 53% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RE
react-router · remix-run
>= 7.0.0, < 7.18.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55685
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55685
Release Notes
https://github.com/remix-run/react-router/blob/main/CHANGELOG.md#v7180
Patch
https://github.com/remix-run/react-router/commit/09e6020d1950e54f361f7ad00938ecd4dde60929
Issue Tracking
https://github.com/remix-run/react-router/pull/15186
Release Notes
https://github.com/remix-run/react-router/releases/tag/react-router@7.18.0
Third Party Advisory
https://github.com/remix-run/react-router/security/advisories/GHSA-8x6r-g9mw-2r78
Third Party Advisory
https://github.com/remix-run/react-router/security/advisories/GHSA-chx6-hx7r-mcp5
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