In Helm 2.x before 2.15.2, commands that deal with loading a chart as a directory or packaging a chart provide an opportunity for a maliciously designed chart to include sensitive content such as /etc/passwd, or to execute a denial of service (DoS) via a special file such as /dev/urandom, via symlinks. No version of Tiller is known to be impacted. This is a client-only issue.
Impact
During a security audit of Helm's code base, Helm maintainers identified a bug in which a Helm plugin can contain duplicates of the same entry, with the last one always used. If a plugin is compromised, this lowers the level of access that an attacker needs to modify a plugin's install hooks, causing a local execution attack.
To perform this attack, an attacker must have write access to the git repository or plugin archive (.tgz) while being downloaded (which can occur during a MITM attack on a non-SSL connection).
Patches
This issue has been patched in Helm 2.16.11 and Helm 3.3.2.
Workarounds
Make sure to install plugins using a secure connection protocol like SSL.
All versions of Helm between Helm >=2.0.0 and < 2.12.2 contains a CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in The commands helm fetch --untar and helm lint some.tgz that can result when chart archive files are unpacked a file may be unpacked outside of the target directory. This attack appears to be exploitable via a victim must run a helm command on a specially crafted chart archive. This vulnerability appears to have been fixed in 2.12.2.
Impact
During a security audit of Helm's code base, security researchers at Trail of Bits identified a bug in which the alias field on a Chart.yaml is not properly sanitized. This could lead to the injection of unwanted information into a chart.
Patches
This issue has been patched in Helm 3.3.2 and 2.16.11
Specific Go Packages Affected helm.sh/helm/v3/pkg/chartutil
Workarounds
Manually review the dependencies field of any untrusted chart, verifying that the alias field is either not used, or (if used) does not contain newlines or path characters.
Impact
During a security audit of Helm's code base, security researchers at Trail of Bits identified a bug in which the a Helm repository can contain duplicates of the same chart, with the last one always used. If a repository is compromised, this lowers the level of access that an attacker needs to inject a bad chart into a repository.
To perform this attack, an attacker must have write access to the index file (which can occur during a MITM attack on a non-SSL connection).
Specific Go Packages Affected helm.sh/helm/v3/pkg/repo
Patches
This issue has been patched in Helm 3.3.2 and 2.16.11
Workarounds
- do not install charts from repositories you do not trust - fetch charts using a secure channel of communication (such as TLS) - use helm pull to fetch the chart, then review the chart’s content (either manually, or with helm verify if it has been signed) to ensure it has not been tampered with - manually review the index file in the Helm repository cache before installing software.
Impact
Security researchers at Trail of Bits discovered that plugin names are not sanitized properly. As a result, a malicious plugin author could use characters in a plugin name that would result in unexpected behavior, such as duplicating the name of another plugin or spoofing the output to helm --help.
Specific Go Packages Affected helm.sh/helm/v3/pkg/plugin
Patches
This issue has been patched in Helm 3.3.2.
Workarounds
Do not install untrusted Helm plugins. Examine the name field in the plugin.yaml file for a plugin, looking for characters outside of the [a-zA-Z0-9.-] range.