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Fencer Vulns
high 7.5

CVE-2026-4867 json

path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters

published 2026-03-26 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-16273

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

Impact:

A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.

Patches:

Upgrade to path-to-regexp@0.1.13

Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.

Workarounds:

All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).

If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.

Patch / fix

  • path-to-regexp path-to-regexp 0.1.13
  • node-path-to-regexp Debian 14, Debian 13, Debian 12 1.0.1-1

debian advisories DEBIAN-CVE-2026-4867

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-2026-4867 updated cvss 5.3

path-to-regexp: path-to-regexp: Denial of Service via catastrophic backtracking from malformed URL parameters

  • Red Hat Cryostat 4 path-to-regexp, cryostat/cryostat-openshift-console-plugin-rhel9 Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/kibana6-rhel8, openshift-logging/elasticsearch6-rhel9, openshift-logging/logging-curator5-rhel9, openshift-logging/elasticsearch-proxy-rhel9, openshift-logging/elasticsearch-rhel9-operator, openshift-logging/elasticsearch-operator-bundle Red Hat Migration Toolkit for Applications 8 mta/mta-ui-rhel9 Red Hat Migration Toolkit for Virtualization mtv-candidate/mtv-console-plugin-rhel9, migration-toolkit-virtualization/mtv-console-plugin-rhel9 Red Hat Multicluster Engine for Kubernetes multicluster-engine/console-mce-rhel9 Red Hat Network Observability Operator network-observability/network-observability-console-plugin-rhel9
    +34 more products
    Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-console-plugin-rhel9, openshift-lightspeed/lightspeed-console-plugin-pf5-rhel9 Red Hat OpenShift Pipelines openshift-pipelines/pipelines-console-plugin-rhel8, openshift-pipelines/pipelines-console-plugin-rhel9 Red Hat OpenShift Service Mesh 2 openshift-service-mesh/kiali-rhel8, openshift-service-mesh/kiali-ossmc-rhel8 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 Red Hat AMQ Broker 7 path-to-regexp, amq7-tech-preview/amq-broker-jolokia-api-server-rhel9 Red Hat Ansible Automation Platform 2 automation-gateway, automation-controller, automation-platform-ui, automation-eda-controller, ansible-automation-platform-26/gateway-rhel9, ansible-automation-platform-tech-preview/mcp-server-rhel9 Red Hat build of Apache Camel - HawtIO 4 path-to-regexp Red Hat build of Apicurio Registry 2 path-to-regexp Red Hat build of OptaPlanner 8 path-to-regexp Red Hat Build of Podman Desktop podman-desktop-macos-1-0, podman-desktop-windows-1-0 Red Hat Data Grid 8 path-to-regexp Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9, rhdh/backstage-community-plugin-catalog-backend-module-scaffolder-relation-processor Red Hat Edge Manager 1 rhem/flightctl-ui-rhel9, rhem/flightctl-ui-ocp-rhel9 Red Hat Enterprise Linux 8 pcs, mozjs60, pcs-snmp Red Hat Enterprise Linux 9 gjs, pcs, sgx-mpa, tdx-qgs, pcs-snmp, sgx-libs, +5 more Red Hat Enterprise Linux 10 linux-sgx Red Hat Fuse 7 path-to-regexp Red Hat JBoss Enterprise Application Platform 7 path-to-regexp Red Hat JBoss Enterprise Application Platform 8 path-to-regexp Red Hat JBoss Enterprise Application Platform Expansion Pack path-to-regexp Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-data-science-pipelines-argo-argoexec-rhel8, rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9, rhoai/odh-data-science-pipelines-argo-workflowcontroller-rhel8 Red Hat OpenShift Container Platform 4 openshift4/ose-console, openshift4/ose-console-rhel9, openshift4/ose-monitoring-plugin-rhel9, openshift4/ose-agent-installer-ui-rhel9 Red Hat Openshift Data Foundation 4 odf4/mcg-core-rhel9, odf4/odf-console-rhel9, odf4/ocs-client-console-rhel9, odf4/odf-multicluster-console-rhel9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9, devspaces/jetbrains-ide-rhel9 Red Hat OpenShift distributed tracing 3 rhosdt/tempo-jaeger-query-rhel9 Red Hat OpenShift GitOps openshift-gitops-1/argocd-rhel8, openshift-gitops-1/argocd-rhel9, openshift-gitops-1/console-plugin-rhel8 Red Hat OpenShift Virtualization 4 container-native-virtualization/kubevirt-console-plugin, container-native-virtualization/kubevirt-console-plugin-rhel9 Red Hat Process Automation 7 path-to-regexp Red Hat Quay 3 quay/quay-rhel8 Red Hat Satellite 6 nodejs-react-router, nodejs-react-router-dom Red Hat Single Sign-On 7 path-to-regexp Red Hat Trusted Artifact Signer rhtas/rhtas-console-ui-rhel9
    affected: workaround, no fix available “Fix deferred”

2 more affected, 1 more fixed, 1 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
7 mo ago

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • path-to-regexp path-to-regexp

Classification

Weakness
  • CWE-1333 Inefficient Regular Expression 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.