DoS via Exponential Regex Expansion in path-to-regexp 8.4.0
CVE-2026-4926 Published on March 26, 2026

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

NVD

Vulnerability Analysis

CVE-2026-4926 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Types

What is a Resource Exhaustion Vulnerability?

The software does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

CVE-2026-4926 has been classified to as a Resource Exhaustion vulnerability or weakness.

What is a ReDoS Vulnerability?

The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles. Some regular expression engines have a feature called "backtracking". If the token cannot match, the engine "backtracks" to a position that may result in a different token that can match. Backtracking becomes a weakness if all of these conditions are met:

CVE-2026-4926 has been classified to as a ReDoS vulnerability or weakness.


Products Associated with CVE-2026-4926

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Red Hat Ansible Automation Platform
 
Red Hat Ansible Automation Platform Developer
 
Red Hat Ansible Automation Platform Inside
 
Red Hat Cryostat
 
Red Hat Migration Toolkit Virtualization
 
Red Hat Rhdh
 
Red Hat Openshift Devspaces
 
Red Hat Openshift Distributed Tracing
 
Red Hat Trusted Artifact Signer
 
Red Hat Logging
 
Red Hat Migration Toolkit Applications
 
Red Hat Multicluster Engine
 
Red Hat Openshift Pipelines
 
Red Hat Acm
 
Red Hat Amq Broker
 
Red Hat Podman Desktop
 
Red Hat Jboss Data Grid
 
Red Hat Edge Manager
 
Red Hat Enterprise Linux (RHEL)
 
Red Hat Jboss Fuse
 
Red Hat Openshift Ai
 
Red Hat Openshift
 
Red Hat Openshift Data Foundation
 
Red Hat Openshift Gitops
 
Red Hat Single Sign On
 
Red Hat Ansible Portal
 
Red Hat Network Observ Optr
 
Red Hat Openshift Lightspeed
 
Red Hat Service Mesh
 
Red Hat Advanced Cluster Security
 
Red Hat Apache Camel Hawtio
 
Red Hat Service Registry
 
Red Hat Jboss Enterprise Application Platform
 
Red Hat Jbosseapxp
 
Red Hat Container Native Virtualization
 
Red Hat Jboss Enterprise Bpms Platform
 
Red Hat Quay
 
Red Hat Satellite
 
Red Hat Trusted Profile Analyzer
 

Affected Versions

path-to-regexp: Red Hat Ansible Automation Platform 2.5 for RHEL 8: Red Hat Ansible Automation Platform 2.5 for RHEL 9: Red Hat Ansible Automation Platform 2.6 for RHEL 9: Red Hat Cryostat 4 on RHEL 9: Red Hat Migration Toolkit for Virtualization 2.1: Red Hat Migration Toolkit for Virtualization 2.9: Red Hat Ansible Automation Platform 2.6: Red Hat Developer Hub 1.8: Red Hat Developer Hub 1.9: Red Hat OpenShift Dev Spaces 3.27: Red Hat OpenShift distributed tracing 3.9.3: Red Hat Trusted Artifact Signer 1.3: Logging Subsystem for Red Hat OpenShift: Red Hat Migration Toolkit for Applications 8: Red Hat Multicluster Engine for Kubernetes: Red Hat OpenShift Pipelines: Red Hat Advanced Cluster Management for Kubernetes 2: Red Hat AMQ Broker 7: Red Hat Ansible Automation Platform 2: Red Hat Build of Podman Desktop: Red Hat Data Grid 8: Red Hat Developer Hub: Red Hat Edge Manager 1: Red Hat Enterprise Linux 9: Red Hat Fuse 7: Red Hat OpenShift AI (RHOAI): Red Hat OpenShift Container Platform 4: Red Hat Openshift Data Foundation 4: Red Hat OpenShift GitOps: Red Hat Single Sign-On 7: Red Hat Self-service automation portal 2: Red Hat Ansible Automation Platform 2.6 for RHEL 10: Red Hat Cryostat 4: Red Hat Network Observability Operator: Red Hat OpenShift Lightspeed: Red Hat OpenShift Service Mesh 2: Red Hat OpenShift Service Mesh 3: Red Hat Advanced Cluster Security 4: Red Hat build of Apache Camel - HawtIO 4: Red Hat build of Apicurio Registry 2: Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 8: Red Hat JBoss Enterprise Application Platform 7: Red Hat JBoss Enterprise Application Platform 8: Red Hat JBoss Enterprise Application Platform Expansion Pack: Red Hat OpenShift Virtualization 4: Red Hat Process Automation 7: Red Hat Quay 3: Red Hat Satellite 6: Red Hat Trusted Profile Analyzer:

Exploit Probability

EPSS
0.46%
Percentile
36.04%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.