CVE-2023-0056

What it actually does

An authenticated remote attacker can trigger uncontrolled resource consumption in HAProxy by presenting a specially crafted malicious server response, leading to service crash and denial of availability.

Why it matters to the business

Disruption of load-balanced services and container platforms across Red Hat ecosystems, resulting in unplanned downtime for applications relying on HAProxy; high ecosystem prevalence increases the scope of potential operational impact.

How an attack unfolds

An attacker with valid credentials deploys a malicious server inside an OpenShift cluster and crafts responses that force HAProxy to allocate excessive resources until the process crashes.

How to fix it

Upgrade HAProxy to a patched release in all affected Red Hat products; monitor vendor advisories for exact fixed versions and apply updates promptly given the 1294 days since disclosure.

How to confirm the fix worked

Confirm HAProxy version against vendor fixed releases, review cluster configurations for removal of any test malicious servers, and verify service stability under simulated load.

Typical attack path

1. Obtain authenticated access to an OpenShift environment
2. Deploy or control a malicious backend server
3. Configure HAProxy to route traffic to the malicious server
4. Send crafted responses that trigger unbounded resource consumption
5. Observe HAProxy crash and service unavailability

How to detect it

Monitor HAProxy process logs and system resource metrics for sudden spikes in memory or CPU usage coinciding with new backend server registrations; review OpenShift audit logs for unusual server additions by authenticated users.

What your security team should do

• Prioritize patching HAProxy across all Red Hat Enterprise Linux, OpenShift, and Ceph deployments
• Restrict authenticated access to backend server registration where possible
• Implement resource limits and monitoring for HAProxy processes
• Review EPSS stability and absence from KEV when scheduling remediation