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.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Path-to-regexp | Pillarjs | 8.0.0 (including) | 8.4.0 (excluding) |
| Cryostat 4 on RHEL 9 | RedHat | cryostat/cryostat-openshift-console-plugin-rhel9:4.2.0-9 | * |
| Red Hat Ansible Automation Platform 2.5 for RHEL 8 | RedHat | automation-gateway-0:2.5.20260422-3.el8ap | * |
| Red Hat Ansible Automation Platform 2.5 for RHEL 9 | RedHat | automation-gateway-0:2.5.20260422-3.el9ap | * |
| Red Hat Ansible Automation Platform 2.6 for RHEL 9 | RedHat | automation-platform-ui-0:2.6.9-1.el9ap | * |
| Migration Toolkit for Virtualization 2.1 | RedHat | migration-toolkit-virtualization/mtv-console-plugin-rhel9:1779139872 | * |
| Migration Toolkit for Virtualization 2.9 | RedHat | migration-toolkit-virtualization/mtv-console-plugin-rhel9:1778927462 | * |
| Red Hat Ansible Automation Platform 2.6 | RedHat | ansible-automation-platform-tech-preview/mcp-server-rhel9:1777386606 | * |
| Red Hat Ansible Automation Platform 2.6 | RedHat | ansible-automation-platform-26/gateway-rhel9:1779773804 | * |
| Red Hat Developer Hub 1.8 | RedHat | rhdh/rhdh-hub-rhel9:1776784286 | * |
| Red Hat Developer Hub 1.9 | RedHat | rhdh/rhdh-hub-rhel9:1777903262 | * |
| Red Hat OpenShift Dev Spaces 3.27 | RedHat | devspaces/code-rhel9:1776744110 | * |
| Red Hat OpenShift Dev Spaces 3.27 | RedHat | devspaces/jetbrains-ide-rhel9:1776795400 | * |
| Red Hat OpenShift distributed tracing 3.9.3 | RedHat | rhosdt/tempo-jaeger-query-rhel9:1776435608 | * |
| Red Hat Trusted Artifact Signer 1.3 | RedHat | rhtas/rhtas-console-ui-rhel9:1776673130 | * |
| Red Hat Trusted Artifact Signer 1.3 | RedHat | rhtas/rhtas-console-ui-rhel9:1776889929 | * |
| Node-path-to-regexp | Ubuntu | esm-apps/xenial | * |
| Node-path-to-regexp | Ubuntu | upstream | * |
Potential Mitigations
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/147.html
- https://cwe.mitre.org/data/definitions/227.html
- https://cwe.mitre.org/data/definitions/492.html