CVE-2026-123865
Description
A flaw was found in Node.js. An unauthenticated remote attacker can cause a Denial of Service (DoS) through resource exhaustion by permanently leaking server memory and file descriptors. By initiating a connection shutdown and sending a protocol-violating HTTP/2 frame, the internal protocol handler terminates the session without Node.js properly releasing the associated state. Over time, an attacker can accumulate dangling connections, ultimately exhausting server resources and disrupting service availability.
Statement
This vulnerability is rated as Important severity because remote, unauthenticated actors can induce memory and file descriptor leaks with minimal effort, resulting in a complete denial of service. Exposure is limited to deployments where Node.js applications directly handle HTTP/2 connections. Applications running standard HTTP/1.1 or those deployed behind front-end reverse proxies that terminate HTTP/2 traffic are not susceptible to this attack.
Mitigation
1. Terminate HTTP/2 at an upstream reverse proxy:
Configure an edge reverse proxy (such as HAProxy, Envoy, or Apache HTTP Server) to handle client HTTP/2 traffic and proxy requests to the backend Node.js application over standard HTTP/1.1. Alternatively, if HTTP/2 capabilities are not required by the application, configure the Node.js application to use the standard `http` or `https` modules instead of `http2`.
2. Restrict network access using firewalld:
If direct exposure cannot be avoided, limit network access to the Node.js HTTP/2 port so only trusted internal clients or reverse proxies can reach it:
firewall-cmd --permanent --zone=trusted --add-source=<TRUSTED_IP_OR_SUBNET>
firewall-cmd --permanent --zone=trusted --add-port=<NODE_PORT>/tcp
firewall-cmd --reload
Caveats:
Restricting access via firewall rules blocks untrusted external networks from communicating directly with the service. Reloading firewalld applies changes immediately. Reconfiguring the Node.js application or underlying service settings requires restarting the Node.js process, which will temporarily interrupt active client connections.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | 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:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Other); DoS: Resource Consumption (Memory); DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Frequently Asked Questions
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