CVE-2026-64676: Kata Containers: Unauthorized mem-agent ttRPC methods let an untrusted host tamper with confidential-guest memory

Vulnerability summary

CVE-2026-64676 is a medium (CVSS 5.7) Missing Authorization vulnerability in kata-containers. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7% of scored vulnerabilities.

Timeline

1. 07-08-2026
   PublishedVulnerability first disclosed.
2. 13-08-2026
   Last modifiedVulnerability information updated.

Description

Kata Containers is an open source implementation of lightweight Virtual Machines (VMs) that perform like containers. In versions prior to 4.0.0, the kata-agent is vulnerable to an authorization bypass in confidential-guest memory management. In Confidential Containers (CoCo) deployments, the kata-agent enforces an OPA/Rego-based AgentPolicy that must authorize every ttRPC API call, forming the security boundary that prevents an untrusted host from directing the confidential guest. Two ttRPC methods introduced with the mem-agent feature are missing this authorization check, so an untrusted host can invoke them unconditionally regardless of the guest's policy configuration. When mem-agent is enabled (off by default), this lets the host tamper with in-guest memory management by forcing swap, aggressive eviction, or compaction, resulting in attacker-controlled availability and performance degradation of the confidential workload entirely outside the agent-policy boundary. The impact does not include memory disclosure or code execution, and severity is bounded by the precondition that mem-agent must be explicitly enabled. This issue is fixed in version 4.0.0.

• CWE-862Missing AuthorizationThe product does not perform an authorization check when an actor attempts to access a resource or perform an action.