CVE-2026-122315 in Kyverno
Summary
by MITRE • 11/05/2026
Kyverno before 1.19.2 contains an unchecked type assertion in buildStatementMap that allows unauthenticated attackers to crash the policy engine via crafted attestation statements. Attackers can push an OCI referrer manifest with a non-string type field to bypass image verification under failurePolicy Ignore or crash-loop the reports-controller.
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Analysis
by VulDB Data Team • 11/05/2026
The vulnerability identified in Kyverno versions prior to 1.19.2 stems from a critical lack of input validation within the buildStatementMap function, specifically regarding the handling of attestation statements derived from OCI referrer manifests. This flaw represents an unchecked type assertion error where the system fails to verify that expected fields are of the correct data type before processing them. In normal operation, Kyverno relies on these attestations to enforce security policies and verify image integrity during deployment workflows. However, when an attacker constructs a malicious OCI referrer manifest containing a field with a non-string type in a location where a string is strictly required by the policy engine logic, the internal assertion mechanism triggers a panic condition rather than gracefully handling the invalid input.
From a technical perspective, this issue classifies as CWE-20 Improper Input Validation combined with CWE-754 Incorrect Check or Call of an Unusual Function, leading to a denial of service through application crash. The attack vector involves pushing a specially crafted OCI referrer manifest that exploits the type mismatch within the attestation structure. Because Kyverno processes these manifests as part of its standard image verification pipeline, no authentication is required for this interaction if the registry allows anonymous pulls or if the attacker has access to push such artifacts into an accessible repository. The failure lies in the assumption that all incoming data adheres to a strict schema without runtime type checking, which violates secure coding principles regarding defensive programming and input sanitization.
The operational impact of this vulnerability is severe for organizations relying on Kyverno for Kubernetes admission control and image policy enforcement. If the system is configured with a failurePolicy set to Ignore, an attacker can bypass critical security checks by causing the verification process to fail silently or incorrectly due to the malformed data type. This allows potentially malicious or unverified images to be deployed into the cluster without proper scrutiny, undermining the entire zero-trust architecture established by the policy engine. Alternatively, if the failurePolicy dictates a stricter response such as Reject, the unchecked assertion causes the reports-controller to crash-loop continuously. This results in a denial of service condition where the Kyverno controller becomes unresponsive, preventing any new policies from being evaluated or existing workloads from being admitted, thereby disrupting cluster operations and potentially leaving other resources unprotected during the outage window.
This vulnerability aligns with MITRE ATT&CK technique T1496 Resource Hijacking in the context of denial of service against control plane components, as well as techniques related to bypassing defenses such as Defense Evasion by exploiting validation logic failures. To mitigate this risk, organizations must immediately upgrade Kyverno to version 1.19.2 or later where the type assertion has been hardened with proper error handling and input validation checks. Additionally, administrators should review their failurePolicy configurations for critical policies to ensure that a single malformed request does not lead to widespread service disruption. Implementing strict registry access controls and validating OCI manifests at the ingress point can further reduce the attack surface by preventing malicious artifacts from reaching the Kyverno processing pipeline in the first place.