CVE-2026-100707
Received Received - Intake

Kyverno Namespace Isolation Bypass via Percent-Encoded Paths

Publication date: 2026-09-26

Last updated on: 2026-09-26

Assigner: VulnCheck

Description
Kyverno before 1.19.1 contains a namespace isolation bypass in the apiCall context entry of namespaced Policy resources due to inconsistent path interpretation between validation and execution. A low-privilege tenant can use percent-encoded dot-segments in urlPath to bypass namespace checks and read resources from other namespaces using the Kyverno admission controller's ServiceAccount credentials.

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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-2026-100707
EUVD
EUVD-2026-87680

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
kyverno kyverno to 1.19.1 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

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Executive Summary

CVE-2026-100707 is a namespace isolation bypass in Kyverno, a Kubernetes policy engine. It occurs due to inconsistent path interpretation between validation and execution in namespaced Policy resources. A low-privilege user can use percent-encoded dot-segments (e.g., %2e%2e) in the urlPath to bypass namespace checks and read resources from other namespaces using the Kyverno admission controller's ServiceAccount credentials.

Detection Guidance

To detect this vulnerability, check Kyverno version with: kubectl get deployment -n kyverno kyverno -o jsonpath='{.spec.template.spec.containers[0].image}'. If version is below 1.19.1, the system is vulnerable. Inspect Policy resources for apiCall context entries with percent-encoded paths like %2e%2e in urlPath fields.

Impact Analysis

This vulnerability allows an attacker with low privileges to read sensitive resources like ConfigMaps or Secrets across namespaces. The impact depends on the Kyverno ServiceAccount permissions. A default installation may allow reading ConfigMaps cluster-wide, while additional permissions could lead to credential theft or potential cluster takeover.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data across namespaces, violating data isolation requirements in GDPR and HIPAA. Exposure of ConfigMaps or Secrets may result in non-compliance with these regulations, potentially leading to legal and financial penalties.

Mitigation Strategies

Upgrade Kyverno to version 1.19.1 or later immediately. Review and restrict permissions of the Kyverno ServiceAccount to minimum required access. Audit existing Policy resources for suspicious apiCall configurations with percent-encoded paths. Monitor admission controller logs for unauthorized namespace access attempts.

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