CVE-2026-123868
Description
A flaw was found in Node.js. An unauthenticated remote attacker can cause a denial of service (DoS) by exhausting server memory. By transmitting streams containing numerous small HTTP/2 data frames, incoming data is queued without being properly accounted against session memory limits. This allows an attacker to consume disproportionate amounts of system memory with relatively little network traffic, ultimately causing the server process to crash.
Statement
Red Hat has rated this vulnerability as Moderate severity because, although an unauthenticated remote attacker can trigger a denial of service, the flaw does not compromise data confidentiality or host integrity. Exploitation requires applications to explicitly implement Node.js native HTTP/2 server capabilities to receive untrusted traffic. In standard enterprise deployments, Node.js services are typically fronted by reverse proxies or ingress gateways, or utilize standard HTTP/1.1, which significantly reduces the likelihood of direct remote exposure.
Mitigation
To mitigate this issue, restrict access to the Node.js application to trusted networks using firewall controls, or deploy an upstream reverse proxy (such as HAProxy or NGINX) to terminate HTTP/2 traffic and forward requests to Node.js using HTTP/1.1. If the application is designed solely for local consumption, bind the listener to localhost (127.0.0.1).
To restrict inbound traffic on the service port to trusted source addresses using firewalld:
firewall-cmd --permanent --zone=trusted --add-source=<TRUSTED_CIDR>
firewall-cmd --permanent --zone=public --remove-port=<PORT>/tcp
firewall-cmd --reload
Caveats:
Restricting access via firewall rules prevents untrusted clients from connecting to the application. Terminating HTTP/2 at an upstream proxy may alter client-side multiplexing characteristics and requires proxy reconfiguration.
Warning: Reloading firewall rules with 'firewall-cmd --reload' applies changes immediately and may disrupt active network 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 | 5.9 | N/A | 5.9 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| 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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
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
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
