Kyverno 1.16.0 through 1.19.0 registers the globalcontext.Lib CEL library in its policy environment without confining it to the policy's namespace, unlike the sibling libraries (resource.Lib, http.Lib, configMap loader) which are handed the policy namespace. A tenant who can create a namespaced policy (e.g. NamespacedValidatingPolicy, and likewise the namespaced mutating, deleting, generating, and image-validating policy kinds) in their own namespace can call globalContext.get("<entry>", "") and receive the full cached contents of a cluster-scoped GlobalContextEntry, including data cached from namespaces the tenant has no RBAC permission to read. No admission validation rejects such calls.
Fixed in 1.19.1.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
None
No data modification
Availability
None
No disruption
CVSS Vector v4.0