Hello!
We want to share an important update about a recent Helm upgrade that may affect your releases.
Background
We recently upgraded from Helm 3.18.3 to 3.18.5 in our air gap bundle builder and other services. This newer version includes a security fix that made JSON schema validation significantly stricter. If your Helm charts use values.schema.json files with "additionalProperties": false, you may encounter deployment failures.
What You Might See
Helm 3.18.5 contains fixes for a couple security advisories:
- Helm Charts with Specific JSON Schema Values Can Cause Memory Exhaustion · Advisory · helm/helm · GitHub
- Incorrect YAML Content Leads To Panic · Advisory · helm/helm · GitHub
Helm 3.18.5 now strictly rejects any properties not explicitly defined in your schema, whereas previous versions ignored undefined properties. Common properties that might be missing from your schema include:
- resources
- autoscaling
- service
- nodeSelector
- tolerations
- And other standard Helm values
Quick Fix
If you’re experiencing immediate deployment failures, you can temporarily resolve this by changing
"additionalProperties": false
to
"additionalProperties": true
in your values.schema.json file.
Proper Solution
The recommended long-term fix is to add proper definitions for all the properties your chart uses in the values.schema.json file. This maintains schema validation while allowing all necessary properties.
Testing Your Charts
We recommend testing your charts with the latest Helm version to ensure compatibility. You can:
1. Install Helm 3.18.5+ locally
2. Run helm template or helm lint on your charts
3. Check for any schema validation errors
What We’re Doing
- Adding monitoring to detect build failure spikes earlier
- Improving our release communication for critical dependency upgrades
- Working on better tooling to help identify compatibility issues before they affect deployments
If you’re experiencing issues related to this change or need help updating your schemas, please don’t hesitate to reach out to our support team.
Thanks for your patience as we work through these infrastructure improvements together!