CVE-2026-124440: Kyverno 1.19.1 Privilege Escalation via apiCall Namespace Clamp Bypass
Kyverno from 1.19.1 before 1.19.2 contains an authorization bypass vulnerability in the apiCall namespace clamp that allows namespace tenants to issue cross-namespace and cluster-scoped API requests by appending malformed percent-escapes to urlPath. Attackers can create namespaced Policies whose apiCall runs as the admission-controller ServiceAccount to read other namespaces' resources and create mutating webhooks, escalating to cluster admin.
Event History
Frequently Asked Questions
Who is exposed to this vulnerability?
Kyverno deployments running version 1.19.1 are affected. The exposed population includes namespace tenants who can create namespaced Kyverno Policies containing apiCall definitions.
What does an attacker need to exploit it?
An attacker needs permission to create a namespaced Policy and must craft its apiCall urlPath with malformed percent-escapes. No user interaction is required, and the apiCall executes using the admission-controller ServiceAccount.
What could a successful attacker do?
They can bypass the namespace restriction to request resources in other namespaces or cluster-scoped resources. The advisory states that they can create mutating webhooks and escalate to cluster administrator privileges.
How can defenders identify possible exploitation?
Review namespaced Kyverno Policies with apiCall entries, particularly urlPath values containing malformed percent-escape sequences. Also investigate unexpected cross-namespace or cluster-scoped API activity performed by the Kyverno admission-controller ServiceAccount.