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Fencer Vulns
high 7.5

CVE-2026-4926 json

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

published 2026-03-26 7 mo ago modified 2026-09-17 52 d ago also GHSA-j3q9-mxjg-w52f , EUVD-2026-16324

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

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
7 mo ago

Exploit prediction

0.80% chance of exploitation in the next 30 days, higher than 57% 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
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 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.