Kyverno versions 1.18.0 through 1.19.1 contain a cache‑bypass flaw (CWE‑367) in the verifyImages policy. The verification results are cached based on the image reference string (e.g., a tag) instead of the verified digest. As a result, an attacker who can submit workloads and modify a registry tag can warm the cache with a signed image, repoint the tag to an unsigned image, and have Kyverno accept the workload as if it were verified. This flaw effectively bypasses authentication checks and allows arbitrary containers, potentially malicious, to run in the cluster with the permissions of the policy being applied.

Kyverno by kyverno, versions 1.18.0 up to and including 1.19.1 are affected. The vulnerability is fixed in Kyverno 1.19.2 and later.

The CVSS score of 8.5 indicates a high severity flaw. The EPSS score is not available, providing no current estimate of exploitation probability, and the vulnerability is not listed in the CISA KEV catalog. An attacker must have the ability to submit workloads to the cluster and manipulate registry tags; with these capabilities they can exploit the cache bypass to introduce unauthenticated workloads. The risk is significant for environments that allow untrusted image sources or where registry tags are mutable.