CVE-2022-29226 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 resides in the OAuth filter implementation in Envoy versions prior to 1.22.1. Specifically, the OAuth filter is designed to validate access tokens to enforce authentication. However, due to a missing authentication mechanism (classified under CWE-306: Missing Authentication for Critical Function), the filter incorrectly assumes that all access tokens attached to incoming requests are valid without performing proper validation. The intended behavior is that when the HMAC signed cookie is missing, Envoy should trigger a full authentication flow to verify the token. Instead, the flawed implementation allows any access token to grant access, effectively bypassing authentication controls. This can lead to unauthorized access to protected resources behind the Envoy proxy. The vulnerability does not require user interaction and can be exploited remotely by sending requests with arbitrary access tokens. There is no known workaround other than upgrading to Envoy version 1.22.1 or later, where the issue has been fixed. No known exploits have been reported in the wild as of the publication date. The vulnerability impacts confidentiality and integrity by allowing unauthorized access, and potentially availability if unauthorized users disrupt services. Given Envoy's role as a critical component in cloud-native infrastructure, this vulnerability poses a significant risk to environments relying on it for secure access control.

For European organizations, the impact of CVE-2022-29226 can be substantial, especially for those leveraging Envoy as part of their cloud-native infrastructure, service mesh, or edge proxy solutions. Unauthorized access due to this vulnerability can lead to data breaches, exposure of sensitive information, and potential lateral movement within networks. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, may face compliance violations under GDPR if unauthorized access results in personal data exposure. Additionally, compromised proxies can undermine trust in digital services and disrupt business operations. The vulnerability's exploitation could also facilitate further attacks, such as privilege escalation or injection of malicious traffic, impacting service integrity and availability. Since Envoy is often deployed in microservices architectures, the vulnerability could affect multiple interconnected services, amplifying the potential damage. The absence of a workaround means organizations must prioritize patching to mitigate risks effectively.

1. Immediate Upgrade: Organizations should upgrade all Envoy proxy instances to version 1.22.1 or later, where the OAuth filter properly validates access tokens. 2. Audit and Inventory: Conduct a thorough inventory of all Envoy deployments to identify affected versions and prioritize patching. 3. Access Controls: Restrict network access to Envoy management and proxy endpoints to trusted administrative networks to reduce exposure. 4. Monitoring and Logging: Enhance monitoring to detect anomalous access patterns or unauthorized requests that may indicate exploitation attempts. 5. Token Validation: Where possible, implement additional token validation mechanisms external to Envoy, such as API gateways or identity providers, to add defense in depth. 6. Incident Response Preparedness: Prepare incident response plans to quickly address any signs of compromise related to this vulnerability. 7. Configuration Review: Review OAuth filter configurations to ensure they align with security best practices and do not rely solely on Envoy's internal validation. 8. Network Segmentation: Segment critical services behind Envoy proxies to limit the blast radius of potential unauthorized access.