CVE-2023-2253

What it actually does

The flaw allows an authenticated user to supply an arbitrarily large integer for the 'n' query parameter on the /v2/_catalog endpoint, triggering allocation of a correspondingly large in-memory string slice that exhausts available heap memory and terminates the registry process.

Why it matters to the business

Service disruption for container image registries, potentially halting CI/CD pipelines, deployments, and runtime operations that depend on the registry in OpenShift environments. With no public fixes listed, organizations must apply vendor patches or implement workarounds promptly to avoid prolonged outages.

How an attack unfolds

An attacker with valid credentials to the registry sends a single GET request to /v2/_catalog?n=<very large number>, causing the server to attempt to allocate an enormous array and crash due to memory exhaustion.

How to fix it

Upgrade affected Red Hat OpenShift components to patched versions once released. In the interim, restrict access to the registry API or implement rate limiting and input validation on the n parameter at a reverse proxy or WAF.

How to confirm the fix worked

Monitor registry logs for requests containing unusually large n values; test by sending controlled large-n requests in a staging environment and confirm memory usage remains bounded after remediation.

Typical attack path

1. Obtain valid registry credentials
2. Craft HTTP GET request to /v2/_catalog with oversized n parameter
3. Observe service crash or high memory consumption leading to DoS

How to detect it

Review web server or registry access logs for GET requests to /v2/_catalog containing the n parameter with values exceeding expected bounds (e.g., >10000); correlate with sudden memory exhaustion or OOMKilled events in container orchestration logs.

• /v2/_catalog?n=999999999
• large n parameter in registry API requests
• OOMKilled events on distribution registry containers

What your security team should do

• Prioritize patching OpenShift registry components as soon as fixes become available
• Implement network-level controls to limit unauthenticated or excessive API calls to the catalog endpoint
• Add monitoring for memory spikes on registry pods