CVE-2026-100704
Received Received - Intake

Kyverno PolicyException Image Signature Bypass

Publication date: 2026-09-26

Last updated on: 2026-09-26

Assigner: VulnCheck

Description
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.

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Meta Information

Published
2026-09-26
Last Modified
2026-09-26
Generated
2026-09-26
AI Q&A
2026-09-26
EPSS Evaluated
N/A
NVD
CVE-2026-100704
EUVD
EUVD-2026-87677

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
kyverno kyverno From 1.14.0 (inc) to 1.19.0 (inc)
kyverno kyverno 1.19.1

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

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Executive Summary

CVE-2026-100704 is a vulnerability in Kyverno, a Kubernetes policy engine. In versions 1.14.0 through 1.19.0, the ImageValidatingPolicy evaluator fails to read the spec.images and spec.allowedValues fields of a PolicyException. This causes any matching PolicyException to skip image signature verification for the entire resource instead of just the listed images or values, allowing unsigned or untrusted images to bypass security controls.

The issue differs from ValidatingPolicy, GeneratingPolicy, and MutatingPolicy, which correctly enforce partial exemptions based on these fields. The vulnerability is fixed in Kyverno version 1.19.1.

Detection Guidance

To detect this vulnerability, check the Kyverno version in your Kubernetes cluster using kubectl get deployment -n kyverno kyverno -o jsonpath='{.spec.template.spec.containers[0].image}'. If the version is between 1.14.0 and 1.19.0, the system is vulnerable.

Impact Analysis

This vulnerability allows unsigned or untrusted images to bypass image signature verification and enter your Kubernetes cluster. If an attacker exploits this, they could deploy malicious or unauthorized images that bypass security controls, potentially leading to unauthorized access, data breaches, or other security incidents.

Compliance Impact

This vulnerability could impact compliance with GDPR, HIPAA, and other regulations that require strict access controls and data integrity. By allowing unsigned images to bypass verification, organizations may fail to meet security requirements for image authenticity and integrity, potentially leading to non-compliance and associated penalties.

Mitigation Strategies

Upgrade Kyverno to version 1.19.1 or later immediately. Use kubectl set image deployment -n kyverno kyverno kyverno=ghcr.io/kyverno/kyverno:v1.19.1 to update. Review PolicyException resources to ensure they are not unintentionally exempting all images.

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