Executive brief
Helm is a package manager used to manage applications on Kubernetes. A vulnerability in how it handles certain package names allows a malicious package to overwrite files in the user's current directory instead of extracting into a new folder. This could lead to the accidental loss or corruption of local configuration files or data when a user downloads and unpacks a specially crafted chart.
Technical details
A path traversal vulnerability (CWE-22) exists in Helm's chart extraction logic. When using 'helm pull --untar', a specially crafted Chart.yaml with a name field containing dot-segments ('.' or '..') can cause the extraction process to 'collapse' the directory structure. Instead of extracting to '<output dir>/<chart name>/', the contents are written directly into '<output dir>/'. While the implementation prevents traversal outside of the designated output directory, it fails to ensure a unique subdirectory is used, allowing an attacker to overwrite existing files within the target destination. This is fixed in Helm v3.20.2 and v4.1.4.
Affected products
- Helm helm <= 3.20.1, <= 4.1.3
Timeline
- 2026-04-09: disclosed
- 2026-04-09: patched
- 2026-04-10: advisory