CVE-2026-42342
Description
A flaw was found in React Router and @remix-run/server-runtime. A remote attacker can exploit this vulnerability by sending certain crafted requests to the __manifest endpoint. This can lead to unbounded path expansion, consuming disproportionate server resources. The primary consequence is a denial of service (DoS), resulting in response time degradation and service unavailability for end users.
Statement
A flaw was found in React Router (Framework Mode) and Remix (@remix-run/server-runtime). Crafted requests to the __manifest endpoint can trigger unbounded path expansion, consuming disproportionate server resources and causing denial of service through response time degradation or complete service unavailability. This only affects applications using React Router Framework Mode or Remix server runtime; applications using Declarative Mode (BrowserRouter) or Data Mode (createBrowserRouter/RouterProvider) are not impacted. In Red Hat products, affected React Router components are used in internal console UIs that are deployed behind authenticated ingress, reducing the attack surface.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Upgrade to a patched version to fully mitigate the issues (ref: https://github.com/remix-run/react-router/security/advisories/GHSA-8x6r-g9mw-2r78).
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Red Hat CVSS v3 Score Explanation
AC:H - Only Framework Mode affected (not Declarative/Data Mode); RH deployments place console UIs behind authenticated ingress. PR:L - RH UI services enforce authentication by default.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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