Kyverno versions 1.11.0 through 1.19.1 contain an unbounded decompression vulnerability in the extractStatement function. Attackers can supply highly compressed Notary attestation layers that exceed the configured maximum payload size. When the controller decompresses these layers, it exhausts memory, leading to out‑of‑memory kills and interruption of the admission controller service, effectively denying service to legitimate requests.

Kyverno, a Kubernetes policy engine, is impacted. All deployments using Kyverno version 1.11.0 up to but not including 1.19.2 are vulnerable. The vulnerability specifically affects the admission controller component that processes Notary attestation layers.

The CVSS score of 8.7 indicates a high severity risk. The presence of an OOM condition means the exploit requires only remote access to the API server that hosts Kyverno or the ability to upload malicious registry referrer artifacts. No remote code execution is possible; the attacker’s objective is to exhaust memory. Because the EPSS score is not available and the vulnerability is not listed in CISA KEV, there is no known widespread exploitation data, but the high CVSS and the nature of the flaw suggest it is a serious risk, especially in environments where admission controller resources are not limited. The likely attack vector is remote submission of a crafted attestation to the Kyverno admission controller via an attacker‑controlled registry referrer.