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Fencer Intel
high 7.5

CVE-2026-4926 json

path-to-regexp vulnerable to Denial of Service via sequential optional groups

published 7mo ago modified last mo. also EUVD-2026-16324 , GHSA-j3q9-mxjg-w52f

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

Impact:

A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service.

Patches:

Fixed in version 8.4.0.

Workarounds:

Limit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.

Patch / fix

  • npm path-to-regexp 8.4.0
  • path-to-regexp path-to-regexp 8.4.0
  • Red Hat Cryostat 4 on RHEL 9 4.2.0-9
  • Red Hat Red Hat Ansible Automation Platform 2.5 for RHEL 8 0:2.5.20260422-3.el8ap
  • Red Hat Red Hat Ansible Automation Platform 2.5 for RHEL 9 0:2.5.20260422-3.el9ap
  • Red Hat Red Hat Ansible Automation Platform 2.6 for RHEL 9 0:2.6.9-1.el9ap
  • Red Hat Migration Toolkit for Virtualization 2.1 1779139872
  • Red Hat Migration Toolkit for Virtualization 2.9 1778927462
  • Red Hat Red Hat Ansible Automation Platform 2.6 1777386606, 1779773804
  • Red Hat Red Hat Developer Hub 1.8 1776784286
  • Red Hat Red Hat Developer Hub 1.9 1777903262
  • Red Hat Red Hat Edge Manager 1.0 1783502438, 1783502765
  • Red Hat Red Hat Edge Manager 1.1 1784126822, 1784127736, 1784194574, 1784194938
  • Red Hat Red Hat Migration Toolkit for Applications 8.1 1785169013
  • Red Hat Red Hat OpenShift AI 2.25 1787801527
  • Red Hat Red Hat OpenShift Dev Spaces 3.27 1776744110, 1776795400
  • Red Hat Red Hat OpenShift distributed tracing 3.9.3 1776435608
  • Red Hat Red Hat Trusted Artifact Signer 1.3 1776673130, 1776889929
  • node-path-to-regexp Debian 14 8.4.0-1

debian advisories DEBIAN-CVE-2026-4926

  • receptor ansible automation platform 2.6 1.6.5-1.el10ap
  • receptor ansible automation platform inside 2.6, ansible automation platform inside 2.5, ansible automation platform developer 2.6 +3 more 1.6.5-1.el9ap
  • receptorctl ansible automation platform 2.6 1.6.5-1.el10ap
  • receptorctl ansible automation platform inside 2.6, ansible automation platform developer 2.6, ansible automation platform 2.6 1.6.5-1.el9ap
  • python3-click ansible automation platform developer 2.6, ansible automation platform 2.6 8.3.3-1.el10ap
  • python3.12-click ansible automation platform inside 2.6, ansible automation platform inside 2.5, ansible automation platform developer 2.6 +3 more 8.3.3-1.el9ap
  • python3.12-pillow ansible automation platform 2.6, ansible automation platform 2.5 12.2.0-1.el9ap
  • automation-controller ansible automation platform developer 2.6, ansible automation platform 2.6 4.7.12-1.el9ap

red hat advisories RHSA-2026:24762RHSA-2026:24761

Is CVE-2026-4926 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-4926 updated cvss 7.5

path-to-regexp: path-to-regexp: Denial of Service via crafted regular expressions

  • 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 Virtualization mtv-candidate/mtv-console-plugin-rhel9 Red Hat OpenShift Pipelines openshift-pipelines/pipelines-console-plugin-rhel9 Red Hat AMQ Broker 7 amq7-tech-preview/amq-broker-jolokia-api-server-rhel9 Red Hat Ansible Automation Platform 2 automation-controller
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Build of Podman Desktop podman-desktop-macos-1-0, podman-desktop-windows-1-0 Red Hat Data Grid 8 org.infinispan-infinispan-console
    affected: workaround, no fix available
  • Red Hat Developer Hub 1 rhdh/backstage-community-plugin-catalog-backend-module-scaffolder-relation-processor
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 9 gjs
    affected: workaround, no fix available
  • Red Hat Fuse 7 io.hawt-project, io.apicurio-apicurito, io.hawt-hawtio-online, io.syndesis-syndesis-parent
    affected: workaround, no fix planned “Will not fix”
  • Red Hat OpenShift Container Platform 4 openshift4/ose-monitoring-plugin-rhel8 Red Hat Openshift Data Foundation 4 odf4/ocs-client-console-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift GitOps openshift-gitops-1/argocd-rhel8, openshift-gitops-1/argocd-rhel9, openshift-gitops-1/console-plugin-rhel8
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Single Sign-On 7 org.keycloak-keycloak-parent
    affected: workaround, no fix planned “Will not fix”
show 21 more
  • Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal
    affected: workaround, no fix available
  • Red Hat Cryostat 4 on RHEL 9 cryostat/cryostat-openshift-console-plugin-rhel9 4.2.0-9
    fixed: vendor fix RHSA-2026:17789
  • Red Hat Migration Toolkit for Virtualization 2.9 migration-toolkit-virtualization 1778927462
    fixed: vendor fix RHSA-2026:19410
  • Red Hat Migration Toolkit for Virtualization 2.10 migration-toolkit-virtualization 1779139872
    fixed: vendor fix RHSA-2026:19409
  • Red Hat Ansible Automation Platform 2.5 for RHEL 8 automation-gateway-server 2.5.20260422-3.el8ap Red Hat Ansible Automation Platform 2.5 for RHEL 9 automation-gateway-server 2.5.20260422-3.el9ap
    fixed: vendor fix RHSA-2026:24761
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-tech-preview 1777386606, ansible-automation-platform-26/gateway-rhel9 1779773804
    fixed: vendor fix RHSA-2026:24866
  • Red Hat Ansible Automation Platform 2.6 for RHEL 9 automation-platform-ui 2.6.9-1.el9ap
    fixed: vendor fix RHSA-2026:24762
  • Red Hat Developer Hub 1.8 rhdh 1776784286
    fixed: vendor fix RHSA-2026:9742
  • Red Hat Developer Hub 1.9 rhdh 1777903262
    fixed: vendor fix RHSA-2026:13826
  • Red Hat Edge Manager 1.0 rhem/flightctl-ui-rhel9 1783502438, rhem/flightctl-ui-ocp-rhel9 1783502765
    fixed: vendor fix RHSA-2026:36651
  • Red Hat Edge Manager 1.1 rhem/flightctl-ui-rhel9 1784127736, rhem/flightctl-ui-rhel10 1784194574, rhem/flightctl-ui-ocp-rhel9 1784126822, rhem/flightctl-ui-ocp-rhel10 1784194938
    fixed: vendor fix RHSA-2026:40945
  • Red Hat Migration Toolkit for Applications 8.1 mta/mta-ui-rhel9 1785169013
    fixed: vendor fix RHSA-2026:50300
  • Red Hat OpenShift AI 2.25 rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 1787801527
    fixed: vendor fix RHSA-2026:65126
  • Red Hat OpenShift Dev Spaces 3.27 devspaces 1776744110, devspaces 1776795400
    fixed: vendor fix RHSA-2026:10175
  • Red Hat OpenShift distributed tracing 3.9.3 rhosdt 1776435608
    fixed: vendor fix RHSA-2026:9385
  • Red Hat Trusted Artifact Signer 1.3 rhtas/rhtas-console-ui-rhel9 1776673130, rhtas/rhtas-console-ui-rhel9 1776889929
    fixed: vendor fix RHSA-2026:10172
  • Red Hat Cryostat 4 io.cryostat-cryostat
    not affected: component not present
  • Red Hat Cryostat 4 on RHEL 9 cryostat/cryostat-rhel9 4.2.0-9, cryostat/cryostat-db-rhel9 4.2.0-13, cryostat/jfr-datasource-rhel9 4.2.0-9, cryostat/cryostat-reports-rhel9 4.2.0-9, cryostat/cryostat-storage-rhel9 4.2.0-13, cryostat/cryostat-operator-bundle 4.2.0-7, +3 more Red Hat Migration Toolkit for Virtualization 2.9 migration-toolkit-virtualization 1779084876, migration-toolkit-virtualization 1779085127, migration-toolkit-virtualization 1779085283, migration-toolkit-virtualization 1779085438, migration-toolkit-virtualization 1779085916, migration-toolkit-virtualization 1779085935, +5 more Red Hat Migration Toolkit for Virtualization 2.10 migration-toolkit-virtualization 1779138168, migration-toolkit-virtualization 1779138199, migration-toolkit-virtualization 1779138211, migration-toolkit-virtualization 1779138271, migration-toolkit-virtualization 1779138320, migration-toolkit-virtualization 1779138332, +7 more
    not affected: vulnerable code not present
  • Red Hat Multicluster Engine for Kubernetes multicluster-engine/console-mce-rhel9 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-console-plugin-pf5-rhel9
    not affected: component not present
  • Red Hat OpenShift Service Mesh 2 openshift-service-mesh/kiali-rhel8, openshift-service-mesh/kiali-ossmc-rhel8
    not affected: vulnerable code not in execute path
  • 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
    not affected: vulnerable code not present

34 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
7mo ago

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-11).

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
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 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 path-to-regexp
>=8.0.0, <8.4.0
8.4.0

Affected products

  • path-to-regexp path-to-regexp
  • Red Hat Cryostat 4 on RHEL 9
  • Red Hat Red Hat Ansible Automation Platform 2.5 for RHEL 8
  • Red Hat Red Hat Ansible Automation Platform 2.5 for RHEL 9
  • Red Hat Red Hat Ansible Automation Platform 2.6 for RHEL 9
  • Red Hat Migration Toolkit for Virtualization 2.1
  • Red Hat Migration Toolkit for Virtualization 2.9
  • Red Hat Red Hat Ansible Automation Platform 2.6
  • Red Hat Red Hat Developer Hub 1.8
  • Red Hat Red Hat Developer Hub 1.9
  • Red Hat Red Hat Edge Manager 1.0
  • Red Hat Red Hat Edge Manager 1.1
  • Red Hat Red Hat Migration Toolkit for Applications 8.1
  • Red Hat Red Hat OpenShift AI 2.25
  • Red Hat Red Hat OpenShift Dev Spaces 3.27
  • Red Hat Red Hat OpenShift distributed tracing 3.9.3
  • Red Hat Red Hat Trusted Artifact Signer 1.3
  • Red Hat Cryostat 4
  • Red Hat Logging Subsystem for Red Hat OpenShift
  • Red Hat Multicluster Engine for Kubernetes
  • Red Hat Network Observability Operator
  • Red Hat OpenShift Lightspeed
  • Red Hat OpenShift Pipelines
  • Red Hat OpenShift Service Mesh 2
  • Red Hat OpenShift Service Mesh 3
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2
  • Red Hat Red Hat Advanced Cluster Security 4
  • Red Hat Red Hat AMQ Broker 7
  • Red Hat Red Hat Ansible Automation Platform 2
  • Red Hat Red Hat build of Apache Camel - HawtIO 4
  • Red Hat Red Hat build of Apicurio Registry 2
  • Red Hat Red Hat Build of Podman Desktop
  • Red Hat Red Hat Data Grid 8
  • Red Hat Red Hat Developer Hub
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Fuse 7
  • Red Hat Red Hat JBoss Enterprise Application Platform 7
  • Red Hat Red Hat JBoss Enterprise Application Platform 8
  • Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack
  • Red Hat Red Hat OpenShift AI (RHOAI)
  • Red Hat Red Hat OpenShift Container Platform 4
  • Red Hat Red Hat Openshift Data Foundation 4
  • Red Hat Red Hat OpenShift GitOps
  • Red Hat Red Hat OpenShift Virtualization 4
  • Red Hat Red Hat Process Automation 7
  • Red Hat Red Hat Quay 3
  • Red Hat Red Hat Satellite 6
  • Red Hat Red Hat Single Sign-On 7

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-1333 Inefficient Regular Expression Complexity

References

Sources

Fencer Intel 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.

The maintainers of pillarjs/path-to-regexp published their own advisory on GitHub. Reviewed sources take precedence over it.