CVE-2024-4437 is a vulnerability classified as uncontrolled resource consumption affecting the etcd package distributed with the Red Hat OpenStack platform. The root cause is an incomplete remediation of a prior vulnerability (CVE-2021-44716) because the etcd package uses the http2 implementation from golang.org/x/net/http2 rather than the version maintained and updated by Red Hat Enterprise Linux (RHEL). This discrepancy means that the vulnerable http2 code is not properly patched in the etcd package as shipped with Red Hat OpenStack, leaving it susceptible to resource exhaustion attacks. An attacker can exploit this vulnerability remotely without authentication or user interaction by sending crafted HTTP/2 requests to the etcd service, causing excessive resource consumption such as CPU or memory exhaustion. This can lead to denial-of-service (DoS) conditions, impacting the availability of etcd, which is a critical distributed key-value store used for configuration and service discovery in OpenStack environments. The vulnerability has a CVSS v3.1 base score of 7.5, reflecting its high severity due to network attack vector, low attack complexity, no privileges required, and no user interaction needed. Although no known exploits have been reported in the wild yet, the presence of this vulnerability in critical cloud infrastructure components like OpenStack makes it a significant risk. The vulnerability was published on May 8, 2024, and is assigned by Red Hat. The fix involves updating the etcd package to use the Red Hat maintained http2 package at compile time, ensuring the vulnerable code is replaced with the patched version. Until patches are applied, affected systems remain vulnerable to potential DoS attacks.

For European organizations, this vulnerability poses a substantial risk to the availability of cloud infrastructure services relying on Red Hat OpenStack. Since etcd is fundamental for OpenStack's operation, resource exhaustion attacks can disrupt cloud management, leading to service outages, degraded performance, and potential cascading failures in dependent services. This can affect public and private cloud deployments, impacting sectors such as finance, telecommunications, government, and critical infrastructure that rely on OpenStack for cloud orchestration. The lack of authentication and user interaction requirements lowers the barrier for exploitation, increasing the threat landscape. Organizations may face operational downtime, increased incident response costs, and reputational damage. Additionally, regulatory compliance frameworks in Europe, such as GDPR, emphasize service availability and resilience, so prolonged outages could have legal and financial consequences. The absence of known exploits currently provides a window for proactive mitigation, but the risk of future exploitation remains high.

1. Immediately audit all Red Hat OpenStack deployments to identify usage of the vulnerable etcd package. 2. Rebuild or update the etcd package to ensure it uses the Red Hat Enterprise Linux maintained http2 package instead of the golang.org/x/net/http2 version. This may require recompiling etcd from source with the correct dependencies or applying vendor patches once released. 3. Monitor etcd service resource consumption closely to detect abnormal spikes indicative of exploitation attempts. 4. Restrict network access to etcd endpoints by implementing strict firewall rules and network segmentation to limit exposure to untrusted networks. 5. Employ rate limiting and connection throttling on etcd HTTP/2 interfaces to mitigate potential resource exhaustion. 6. Stay updated with Red Hat security advisories and apply official patches as soon as they become available. 7. Consider deploying redundancy and failover mechanisms for etcd clusters to maintain availability during attack attempts. 8. Conduct penetration testing and vulnerability scanning focused on etcd and OpenStack components to validate mitigation effectiveness. 9. Educate cloud infrastructure teams about this vulnerability and response procedures to ensure rapid incident handling.