Helm Missing Provenance Vulnerability Bypasses Signature Verification

A vulnerability exists in Helm, a package manager for Kubernetes, in versions 4.0.0 through 4.1.3. When signature verification is required, Helm will incorrectly install plugins that lack a provenance file. This oversight allows unsigned plugins to be installed, potentially enabling them to execute arbitrary code by exploiting plugin hooks.

Impact

The vulnerability could lead to the installation of unsigned plugins, which could then execute arbitrary code by using the plugin's hooks.

Reproduction

To reproduce this vulnerability, install a plugin from a tarball that does not include a .prov file, while signature verification is enabled. Helm will issue a warning about the missing provenance file but will still install the plugin. After installation, the plugin can be activated, allowing any embedded malicious code to run.

Remediation

Users should upgrade to Helm version 4.1.4, where this vulnerability is fixed. Instructions for downloading Helm v4.1.4 are available on the Helm GitHub releases page.