Helm v3.21.1 is a stabilization release focusing on hardening the tool against crashes in client-side workflows and addressing security vulnerabilities. It also ensures smoother OCI registry interactions and updates the underlying Go environment to the latest version.

Fix Nil Pointer Panic in Client-Only Operations — Resolves an application crash (panic) when using 'helm template' or 'helm install' in local-only modes, particularly when dealing with Custom Resource Definitions (CRDs). This ensures more predictable behavior during chart development and CI/CD linting stages.

Critical Security and Tooling Updates — Addresses a known vulnerability (GO-2026-5026) in networking libraries and updates the Go runtime to 1.26. Staying current on these dependencies is critical for maintaining the security posture of your deployment pipeline.

Persistent Registry Credentials on HTTP Fallback — Ensures that registry authentication is maintained even if the connection falls back to plain HTTP. This prevents sudden 'unauthorized' errors for users operating in specific air-gapped or internal registry configurations.