Kyverno before version 1.19.1 contains a namespace isolation bypass vulnerability (CVE-2026-100707) in the apiCall context entry of namespaced Policy resources. The root cause is inconsistent path interpretation between validation and execution phases. Specifically, a low-privilege tenant can craft percent-encoded dot-segments in the urlPath to circumvent namespace checks, thereby accessing resources in other namespaces via the Kyverno admission controller's ServiceAccount credentials. This vulnerability has a CVSS 3.1 score of 7.7, indicating high severity, with network attack vector, low attack complexity, low privileges required, no user interaction, and a scope change. The impact is high confidentiality loss without integrity or availability impact.

An attacker with low privileges in a Kubernetes cluster using Kyverno before 1.19.1 can bypass namespace isolation controls and read resources from other namespaces. This leads to a high confidentiality impact as sensitive data from other namespaces can be accessed. There is no reported impact on integrity or availability. The vulnerability leverages the admission controller's ServiceAccount credentials, potentially exposing cluster-wide sensitive information.

A fix is available in Kyverno version 1.19.1. Users should upgrade to version 1.19.1 or later to remediate this namespace isolation bypass vulnerability. No other mitigation guidance is provided or required beyond applying the official patch.