CVE-2026-122306
Received Received - Intake

Kyverno Admission Controller DoS via Wildcard Patterns

Publication date: 2026-11-05

Last updated on: 2026-11-05

Assigner: VulnCheck

Description
Kyverno before 1.19.2 contains a denial of service vulnerability that allows namespaced policy authors to exhaust admission controller CPU by submitting pathological wildcard patterns. Attackers can create a Policy with crafted match and exclude names evaluated by ValidateMatchExcludeConflict, pinning cores and causing cluster-wide webhook timeouts that block resource operations.

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Meta Information

Published
2026-11-05
Last Modified
2026-11-05
Generated
2026-11-05
AI Q&A
2026-11-05
EPSS Evaluated
N/A
NVD
CVE-2026-122306
EUVD
EUVD-2026-117217

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
kyverno kyverno 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-407 An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

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Executive Summary

This is a denial-of-service (DoS) vulnerability in Kyverno versions before 1.19.2. It occurs due to inefficient wildcard matching in the ValidateMatchExcludeConflict function. Attackers exploit this by creating a policy with specially crafted match and exclude names, causing the admission controller to consume excessive CPU resources. This leads to pinned CPU cores and cluster-wide webhook timeouts, blocking legitimate resource operations.

Detection Guidance

Monitor Kyverno admission controller CPU usage for sustained spikes. Check webhook timeout logs for cluster-wide delays. Inspect Kyverno policy evaluations for patterns causing high CPU load. Use metrics endpoints to track ValidateMatchExcludeConflict processing times.

Impact Analysis

This vulnerability can cause severe performance degradation in your Kubernetes cluster. It may lead to CPU exhaustion, webhook timeouts, and blockage of resource operations. Even after API timeouts, background controllers continue re-evaluating policies, prolonging CPU usage and disrupting normal cluster operations.

Mitigation Strategies

Upgrade Kyverno to version 1.19.2 or later immediately. Disable wildcard patterns in policies if possible. Implement rate limiting for policy submissions. Monitor and block suspicious policy creation attempts.

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