CVE-2022-29228 is a vulnerability identified in the Envoy proxy, a widely used cloud-native high-performance proxy that facilitates service mesh and edge proxy functionalities. The issue specifically affects versions prior to 1.22.1 of Envoy. The vulnerability arises within the OAuth filter implementation, where after emitting a local response, the filter erroneously attempts to invoke the remaining filters in the chain by calling continueDecoding(). This behavior violates the expected filter lifecycle, as continueDecoding() should never be called after a local reply has been sent. In newer versions of Envoy, this triggers an ASSERT() failure, effectively halting execution to prevent further damage. However, in earlier versions, this leads to memory corruption, which can cause undefined behavior including crashes or potential exploitation. The root cause is classified under CWE-617 (Reachable Assertion), indicating that an assertion can be triggered in reachable code paths, potentially leading to denial of service or memory corruption. There are no known workarounds for this vulnerability, and the recommended remediation is to upgrade Envoy to version 1.22.1 or later where the issue has been fixed. No public exploits have been reported in the wild, and the vulnerability requires that the OAuth filter be in use, which is common in environments leveraging OAuth for authentication and authorization within microservices architectures or API gateways.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Envoy as part of their cloud-native infrastructure, service mesh deployments (e.g., Istio), or API gateways. The vulnerability can lead to memory corruption or assertion failures, resulting in service crashes or denial of service conditions. This can disrupt critical business applications, degrade service availability, and potentially expose the environment to further exploitation if attackers can leverage the memory corruption to execute arbitrary code. Confidentiality and integrity impacts are less direct but cannot be entirely ruled out if memory corruption is exploited. Organizations in sectors such as finance, telecommunications, healthcare, and government, which often deploy Envoy for secure and scalable service communication, may face operational disruptions and compliance risks. Given the lack of known exploits, the immediate risk is moderate, but the potential for future exploitation remains if the vulnerability is not addressed.

The primary and most effective mitigation is to upgrade Envoy to version 1.22.1 or later, where the issue has been resolved. Organizations should audit their environments to identify all instances of Envoy running versions prior to 1.22.1, including those embedded within service mesh solutions like Istio or other platforms. Since no workarounds exist, patch management processes should prioritize this upgrade. Additionally, organizations should implement runtime monitoring and anomaly detection to identify unexpected crashes or assertion failures in Envoy instances. Employing strict network segmentation and limiting exposure of Envoy proxies to untrusted networks can reduce attack surface. For environments where immediate upgrade is not feasible, temporarily disabling the OAuth filter or replacing it with alternative authentication mechanisms may reduce risk, though this may impact functionality. Finally, maintaining up-to-date backups and incident response plans will help mitigate potential service disruptions.