CVE-2022-29227 is a use-after-free vulnerability (CWE-416) affecting Envoy proxy versions prior to 1.22.1. Envoy is a widely used cloud-native high-performance edge, middle, and service proxy that handles HTTP traffic routing and management. The vulnerability arises when Envoy attempts to send an internal redirect for an HTTP request containing more than just HTTP headers. Specifically, during the replay of such a request, if Envoy sends a local reply while processing the redirect headers, the downstream state incorrectly indicates that the downstream stream is incomplete. Consequently, when Envoy attempts to reset the upstream stream, it mistakenly operates on a stream that is already complete and deleted, leading to a use-after-free condition. This memory corruption flaw can cause crashes or potentially enable remote code execution or denial of service if exploited. No known public exploits have been reported in the wild to date. The recommended remediation is to upgrade Envoy to version 1.22.1 or later, where this issue is fixed. For users unable to upgrade immediately, disabling internal redirects can mitigate crash occurrences related to this vulnerability.

For European organizations, the impact of this vulnerability depends on the extent to which Envoy proxy is deployed within their infrastructure. Envoy is commonly used in cloud-native environments, microservices architectures, and service mesh implementations, which are prevalent in sectors such as finance, telecommunications, and critical infrastructure. Exploitation could lead to service disruptions due to crashes or potentially allow attackers to execute arbitrary code or escalate privileges within the proxy environment, compromising confidentiality, integrity, and availability of network traffic. This could result in data breaches, interception or manipulation of sensitive communications, and operational downtime. Given Envoy’s role as a traffic proxy, successful exploitation could also facilitate lateral movement within networks. Although no active exploits are known, the vulnerability’s presence in widely deployed proxy infrastructure poses a significant risk if left unpatched.

1. Immediate upgrade of Envoy proxy instances to version 1.22.1 or later is the primary and most effective mitigation. 2. For environments where upgrading is not immediately feasible, disable internal redirects in Envoy configurations to prevent triggering the use-after-free condition. 3. Conduct thorough inventory and auditing of all Envoy deployments across the organization to identify affected versions. 4. Implement enhanced monitoring and logging around Envoy proxy processes to detect abnormal crashes or suspicious behavior indicative of exploitation attempts. 5. Employ network segmentation and strict access controls to limit exposure of Envoy instances to untrusted networks or users. 6. Integrate vulnerability scanning and patch management workflows specifically targeting cloud-native infrastructure components like Envoy. 7. Engage with cloud service providers or managed service vendors to ensure their Envoy components are updated and secured. These steps go beyond generic advice by focusing on configuration changes, operational monitoring, and supply chain considerations specific to Envoy deployments.