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Fencer Vulns
high 7.5

CVE-2026-55685 json

React Router: Unauthenticated Denial of Service via Inefficient Route Matching

published 2026-07-24 3 mo ago modified 2026-10-24 15 d ago also GHSA-chx6-hx7r-mcp5 , EUVD-2026-49634

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 53%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm react-router 7.18.0
  • shopify react-router 7.18.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-55685 updated cvss 6.5

react-router: @remix-run/server-runtime: React Router: Denial of Service via unauthenticated manifest endpoint requests

  • Red Hat Exploit Intelligence exploit-intelligence-tech-preview/agent-client-rhel9
    affected: workaround, no fix available
  • Red Hat Network Observability Operator network-observability/network-observability-console-plugin-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-console-plugin-rhel9, openshift-lightspeed/lightspeed-agentic-console-rhel9 Red Hat OpenShift Pipelines openshift-pipelines/pipelines-console-plugin-rhel9 Red Hat Ansible Automation Platform 2 automation-platform-ui 2.6.11-1.el9ap, ansible-automation-platform-26/gateway-rhel9, ansible-automation-platform-27/gateway-rhel9, ansible-on-clouds/aoc-azure-aap-installer-rhel9 Red Hat build of Apicurio Registry 3 apicurio/apicurio-registry-ui-rhel8 Red Hat Data Grid 8 react-router 5.3.4
    +8 more products
    Red Hat Enterprise Linux 9 ipa-client, ipa-common, ipa-server, ipa-selinux, ipa-client-epn, ipa-server-dns, +13 more Red Hat Enterprise Linux 10 ipa 4.13.1-4.el10 Red Hat OpenShift Container Platform 4 openshift4/ose-console-rhel9, openshift4/ose-monitoring-plugin-rhel9 Red Hat OpenShift Container Platform 5 openshift5/ose-console-rhel9, openshift5/ose-monitoring-plugin-rhel9, openshift5/ose-agent-installer-ui-rhel9 Red Hat OpenShift Virtualization 4 container-native-virtualization/kubevirt-console-plugin-rhel9 Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9 Red Hat Trusted Profile Analyzer rhtpa/rhtpa-rhel10 Red Hat Secrets Management Console for Red Hat OpenShift external-secrets-management/console-plugin-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift AI 2.25 rhoai/odh-dashboard-rhel9 1788312226, rhoai/odh-mod-arch-model-registry-rhel9 1788312157
    fixed: vendor fix RHSA-2026:65126
  • Red Hat OpenShift AI 3.4 rhoai/odh-dashboard-rhel9 1787347991, rhoai/odh-mod-arch-maas-rhel9 1787251250, rhoai/odh-mod-arch-automl-rhel9 1787250508, rhoai/odh-mod-arch-gen-ai-rhel9 1786611759, rhoai/odh-mod-arch-mlflow-rhel9 1786612219, rhoai/odh-mod-arch-autorag-rhel9 1787251550, +2 more
    fixed: vendor fix RHSA-2026:60520
  • Red Hat Cryostat 4 react-router 5.3.4, grafana-infinity-datasource-npm 3.7.2_redhat_00002-1, cryostat-openshift-console-plugin-npm 4.2.0_redhat_00003-1 Red Hat Gatekeeper 3 gatekeeper/gatekeeper-rhel9 Red Hat Migration Toolkit for Applications 8 mta/mta-ui-rhel8, mta/mta-ui-rhel9 Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-ui-rhel8 Red Hat Migration Toolkit for Virtualization migration-toolkit-virtualization/mtv-console-plugin-rhel9 Red Hat Multicluster Engine for Kubernetes multicluster-engine/console-mce-rhel9
    +17 more products
    Red Hat Network Observability Operator network-observability/network-observability-console-plugin-pf4-rhel9, network-observability/network-observability-console-plugin-pf5-rhel9 Red Hat Node HealthCheck Operator workload-availability/node-healthcheck-rhel9-operator, workload-availability/node-healthcheck-operator-bundle, workload-availability/node-healthcheck-must-gather-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-console-plugin-419-rhel9, openshift-lightspeed/lightspeed-console-plugin-pf5-rhel9 Red Hat OpenShift Pipelines openshift-pipelines/pipelines-hub-ui-rhel8, openshift-pipelines/pipelines-hub-ui-rhel9, openshift-pipelines/pipelines-console-plugin-rhel8, openshift-pipelines/pipelines-console-plugin-pf5-rhel9 Red Hat OpenShift Service Mesh 3 openshift-service-mesh/kiali-rhel9, openshift-service-mesh/kiali-ossmc-rhel9, openshift-service-mesh/kiali-rhel9-operator, openshift-service-mesh/kiali-operator-bundle Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/console-rhel9 Red Hat Advanced Cluster Security 4 advanced-cluster-security/rhacs-main-rhel8, advanced-cluster-security/rhacs-main-rhel9 Red Hat AMQ Broker 7 react-router 5.3.4 Red Hat Ansible Automation Platform 2 automation-hub 4.9.8-1.el9ap, python-galaxy-ng 4.9.5-1.el9ap, python3x-galaxy-ng 4.9.5-1.el8ap, python3.11-galaxy-ng 4.9.5-2.el9ap, python3.12-galaxy-ng 4.9.8-1.el9ap, automation-controller 4.5.34-1.el9ap, +2 more Red Hat build of Apache Camel - HawtIO 4 react-router 5.3.4 Red Hat build of Apache Camel for Spring Boot 4 react-router 5.3.4 Red Hat Build of Keycloak react-router 5.3.4 Red Hat Build of Podman Desktop rh-podman-desktop.git 1.1.0 Red Hat Ceph Storage 5 rhceph/rhceph-5-dashboard-rhel8 Red Hat Ceph Storage 9 rhceph/alloy-rhel10 Red Hat Connectivity Link 1 rhcl-1/rhcl-console-plugin-rhel9 Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9
    not affected: vulnerable code not present

21 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.71% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.7 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
CNA 4.0 8.7 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm react-router
>=7.0.0, <7.18.0
7.18.0

Affected products

  • remix-run react-router

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-407 Inefficient Algorithmic Complexity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.