Kyverno before 1.19.2 Denial of Service via Shallow Variable Substitution Panic

Summary

Kyverno before 1.19.2 contains an unchecked type assertion in its variable-substitution engine that allows users who can submit resources to crash the policy engine. Attackers can submit resources with non-string fields referenced by {{- variable }} shallow substitution in policies, causing a panic that yields webhook denial of service and policy bypass under failurePolicy Ignore.

Remediation

1. Inventory every kyverno kyverno deployment, including staging.
2. Upgrade kyverno kyverno to 1.19.2.
3. Confirm the running version after the upgrade.

References

• Advisoryhttps://github.com/kyverno/kyverno/security/advisories/GHSA-x4xq-p8g4-6fwg
• Advisoryhttps://www.vulncheck.com/advisories/kyverno-before-1.19.2-denial-of-service-via-shallow-variable-substitution-panic