Bug 2541858 (CVE-2026-100704)

Summary: CVE-2026-100704 github.com/kyverno/kyverno: Kyverno: Image signature verification bypass via improper policy exception evaluation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: gbenhaim, niyer, twaugh
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Kyverno. When evaluating image validation policies, the policy exception handler fails to restrict exemptions to specific designated images, applying the exception to all images within a matching resource instead. An authenticated user can exploit this vulnerability to bypass image signature verification controls, allowing untrusted or unsigned container images to be admitted into the Kubernetes cluster.
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Description OSIDB Bzimport 2026-09-26 13:36:46 UTC 
Kyverno is a policy engine for Kubernetes. In versions 1.14.0 through 1.19.0, the ImageValidatingPolicy (policies.kyverno.io/v1beta1) evaluator never reads the spec.images and spec.allowedValues fields of a PolicyException. Any PolicyException whose policyRefs and matchConditions match a resource causes image signature verification to be skipped for the entire resource rather than only for the listed images or values, so an exception intended to exempt a single trusted image exempts every image on the matched resource(s). As a result, unsigned or untrusted images can be admitted to the cluster without signature verification. This differs from ValidatingPolicy, GeneratingPolicy, and MutatingPolicy, which treat the same field as a partial exemption. The issue is fixed in version 1.19.1.