GHSA-hr2v-4r36-88hr — Helm Chart extraction output directory collapse via `Chart.yaml` name dot-segment

Affected: Go: helm.sh/helm/v4, Go: helm.sh/helm/v3

Helm is a package manager for Charts for Kubernetes. In Helm versions <=3.20.1 and <=4.1.3, a specially crafted Chart will cause `helm pull --untar [chart URL | repo/chartname]` to write the Chart's contents to the immediate output directory (as defaulted to the current working directory; or as given by the `--destination` and `--untardir` flags), rather than the expected output directory suffixed by the chart's name.

### Impact

The bug enables writing the Chart's contents (unpackaged/untar'ed) to the output directory `<output dir>/`, instead of the expected `<output dir>/<chart name>/`, potentially overwriting the contents of the targeted directory.

Note: a chart name containing POSIX dot-dot, or dot-dot and slashes (as if to refer to parent directories) do not resolve beyond the output directory as designed.

### Patches

This issue has been resolved in Helm v3.20.2 and v4.1.3

A Chart with an unexpected name (those specified to be "." or ".."), or a Chart name which results in a non-unique directory will be rejected.

### Workarounds

Ensure the the name of the Chart does not comprise/contain POSIX pathname special directory references ie. dot-dot ("..") or dot ("."). In addition, ensuring that the `pull --untar` flag (or equivalent SDK option) refers to a unique/empty output directory prevents chart extraction from inadvertently overwriting existing files within the specified directory.

### Credits

Oleh Konko @1seal

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GHSA-hr2v-4r36-88hr — Helm Chart extraction output directory collapse via `Chart.yaml` name dot-segment