CVE-2022-29225 is a vulnerability affecting Envoy proxy versions prior to 1.22.1, classified under CWE-400 (Uncontrolled Resource Consumption) and CWE-409 (Improper Handling of Highly Compressed Data). Envoy is a widely used cloud-native high-performance proxy that handles network traffic in modern microservices and cloud environments. The vulnerability arises from the way Envoy's decompression logic manages compressed payloads. Specifically, the decompressor accumulates decompressed data into an intermediate buffer before overwriting the body during the decode/encodeBody process. This design flaw allows an attacker to craft a maliciously compressed payload, such as a zip bomb, which is a small compressed file that expands to consume excessive system memory when decompressed. By sending such a payload, an attacker can trigger uncontrolled resource consumption, leading to exhaustion of system memory and resulting in a denial-of-service (DoS) condition. This vulnerability does not require authentication or user interaction, as it can be exploited by sending specially crafted network traffic to the Envoy proxy. Although no known exploits have been reported in the wild, the risk remains significant due to the potential for service disruption. The recommended remediation is to upgrade Envoy to version 1.22.1 or later, where this issue has been addressed. For users unable to upgrade promptly, disabling decompression functionality can serve as a temporary mitigation to prevent exploitation.

For European organizations, the impact of CVE-2022-29225 can be substantial, particularly for those relying on Envoy proxies in their cloud-native infrastructure, microservices architectures, or service mesh deployments. Exploitation can lead to denial-of-service conditions, causing service outages or degraded performance. This can disrupt critical business operations, especially in sectors such as finance, telecommunications, healthcare, and government services, where high availability and reliability are paramount. Additionally, DoS attacks can be leveraged as part of multi-vector attacks or to distract security teams while other intrusions occur. The uncontrolled resource consumption may also increase operational costs due to the need for emergency incident response and potential hardware resource scaling. Given the widespread adoption of Envoy in European cloud environments and service mesh solutions, the vulnerability poses a risk to both private enterprises and public sector organizations.

1. Immediate upgrade to Envoy version 1.22.1 or later is the most effective mitigation to eliminate the vulnerability. 2. For environments where upgrading is not immediately feasible, disable decompression features in Envoy to prevent processing of compressed payloads that could trigger the vulnerability. 3. Implement network-level filtering to detect and block suspiciously compressed payloads or unusually small compressed files that expand disproportionately, using intrusion detection/prevention systems (IDS/IPS) or web application firewalls (WAFs) with custom rules. 4. Monitor Envoy proxy logs and system resource usage closely for signs of abnormal memory consumption or repeated decompression failures, which may indicate attempted exploitation. 5. Employ rate limiting and traffic anomaly detection to reduce the risk of volumetric attacks leveraging this vulnerability. 6. Conduct regular security assessments and penetration testing focusing on decompression and payload handling to identify potential weaknesses. 7. Maintain an up-to-date inventory of Envoy deployments and ensure patch management processes prioritize this vulnerability.