Medium severity4.4NVD Advisory· Published Apr 9, 2026· Updated Apr 16, 2026

CVE-2026-35206

Description

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. This vulnerability is fixed in 3.20.2 and 4.1.4.

Affected packages

Versions sourced from the GitHub Security Advisory.

Package	Affected versions	Patched versions
helm.sh/helm/v4Go	< 4.1.4	4.1.4
helm.sh/helm/v3Go	< 3.20.2	3.20.2

Affected products

Helm/Helm
cpe:2.3:a:helm:helm:*:*:*:*:*:*:*:*
Range: <3.20.2

Patches

4e7994d44671

fix: Chart dot-name path bug

https://github.com/helm/helmGeorge JenkinsMar 6, 2026via ghsa

commit

14 files changed · +252 −0

internal/chart/v3/metadata.go+3 −0 modified

@@ -112,6 +112,9 @@ func (md *Metadata) Validate() error {
 		return ValidationError("chart.metadata.name is required")
 	}
 
+	if md.Name == "." || md.Name == ".." {
+		return ValidationErrorf("chart.metadata.name %q is not allowed", md.Name)
+	}
 	if md.Name != filepath.Base(md.Name) {
 		return ValidationErrorf("chart.metadata.name %q is invalid", md.Name)
 	}

internal/chart/v3/metadata_test.go+10 −0 modified

@@ -40,6 +40,16 @@ func TestValidate(t *testing.T) {
 			&Metadata{APIVersion: "v3", Version: "1.0"},
 			ValidationError("chart.metadata.name is required"),
 		},
+		{
+			"chart with dot name",
+			&Metadata{Name: ".", APIVersion: "v3", Version: "1.0"},
+			ValidationError("chart.metadata.name \".\" is not allowed"),
+		},
+		{
+			"chart with dotdot name",
+			&Metadata{Name: "..", APIVersion: "v3", Version: "1.0"},
+			ValidationError("chart.metadata.name \"..\" is not allowed"),
+		},
 		{
 			"chart without name",
 			&Metadata{Name: "../../test", APIVersion: "v3", Version: "1.0"},

internal/chart/v3/util/expand.go+17 −0 modified

@@ -52,6 +52,17 @@ func Expand(dir string, r io.Reader) error {
 		return errors.New("chart name not specified")
 	}
 
+	// Reject chart names that are POSIX path dot-segments or dot-dot segments or contain path separators.
+	// A dot-segment name (e.g. ".") causes SecureJoin to resolve to the root
+	// directory and extraction then to write files directly into that extraction root
+	// instead of a per-chart subdirectory.
+	if chartName == "." || chartName == ".." {
+		return fmt.Errorf("chart name %q is not allowed", chartName)
+	}
+	if chartName != filepath.Base(chartName) {
+		return fmt.Errorf("chart name %q must not contain path separators", chartName)
+	}
+
 	// Find the base directory
 	// The directory needs to be cleaned prior to passing to SecureJoin or the location may end up
 	// being wrong or returning an error. This was introduced in v0.4.0.
@@ -61,6 +72,12 @@ func Expand(dir string, r io.Reader) error {
 		return err
 	}
 
+	// Defense-in-depth: the chart directory must be a subdirectory of dir,
+	// never dir itself.
+	if chartdir == dir {
+		return fmt.Errorf("chart name %q resolves to the extraction root", chartName)
+	}
+
 	// Copy all files verbatim. We don't parse these files because parsing can remove
 	// comments.
 	for _, file := range files {

internal/chart/v3/util/expand_test.go+84 −0 modified

@@ -17,11 +17,73 @@ limitations under the License.
 package util
 
 import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
+// makeTestChartArchive builds a gzipped tar archive from the given sourceDir directory, file entries are prefixed with the given chartName
+func makeTestChartArchive(t *testing.T, chartName, sourceDir string) *bytes.Buffer {
+	t.Helper()
+
+	var result bytes.Buffer
+	gw := gzip.NewWriter(&result)
+	tw := tar.NewWriter(gw)
+
+	dir := os.DirFS(sourceDir)
+
+	writeFile := func(relPath string) {
+		t.Helper()
+		f, err := dir.Open(relPath)
+		require.NoError(t, err)
+
+		fStat, err := f.Stat()
+		require.NoError(t, err)
+
+		err = tw.WriteHeader(&tar.Header{
+			Name: filepath.Join(chartName, relPath),
+			Mode: int64(fStat.Mode()),
+			Size: fStat.Size(),
+		})
+		require.NoError(t, err)
+
+		data, err := fs.ReadFile(dir, relPath)
+		require.NoError(t, err)
+		tw.Write(data)
+	}
+
+	err := fs.WalkDir(dir, ".", func(path string, d os.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+
+		if d.IsDir() {
+			return nil
+		}
+
+		writeFile(path)
+
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = tw.Close()
+	require.NoError(t, err)
+	err = gw.Close()
+	require.NoError(t, err)
+
+	return &result
+}
+
 func TestExpand(t *testing.T) {
 	dest := t.TempDir()
 
@@ -75,6 +137,28 @@ func TestExpand(t *testing.T) {
 	}
 }
 
+func TestExpandError(t *testing.T) {
+	tests := map[string]struct {
+		chartName string
+		chartDir  string
+		wantErr   string
+	}{
+		"dot name":      {"dotname", "testdata/dotname", "not allowed"},
+		"dotdot name":   {"dotdotname", "testdata/dotdotname", "not allowed"},
+		"slash in name": {"slashinname", "testdata/slashinname", "must not contain path separators"},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			archive := makeTestChartArchive(t, tt.chartName, tt.chartDir)
+
+			dest := t.TempDir()
+			err := Expand(dest, archive)
+			assert.ErrorContains(t, err, tt.wantErr)
+		})
+	}
+}
+
 func TestExpandFile(t *testing.T) {
 	dest := t.TempDir()

internal/chart/v3/util/testdata/dotdotname/Chart.yaml+4 −0 added

@@ -0,0 +1,4 @@
+apiVersion: v3
+name: ..
+description: A Helm chart for Kubernetes
+version: 0.1.0
\ No newline at end of file

internal/chart/v3/util/testdata/dotname/Chart.yaml+4 −0 added

@@ -0,0 +1,4 @@
+apiVersion: v3
+name: .
+description: A Helm chart for Kubernetes
+version: 0.1.0
\ No newline at end of file

internal/chart/v3/util/testdata/slashinname/Chart.yaml+4 −0 added

@@ -0,0 +1,4 @@
+apiVersion: v3
+name: a/../b
+description: A Helm chart for Kubernetes
+version: 0.1.0
\ No newline at end of file

pkg/chart/v2/metadata.go+3 −0 modified

@@ -112,6 +112,9 @@ func (md *Metadata) Validate() error {
 		return ValidationError("chart.metadata.name is required")
 	}
 
+	if md.Name == "." || md.Name == ".." {
+		return ValidationErrorf("chart.metadata.name %q is not allowed", md.Name)
+	}
 	if md.Name != filepath.Base(md.Name) {
 		return ValidationErrorf("chart.metadata.name %q is invalid", md.Name)
 	}

pkg/chart/v2/metadata_test.go+10 −0 modified

@@ -40,6 +40,16 @@ func TestValidate(t *testing.T) {
 			&Metadata{APIVersion: "v2", Version: "1.0"},
 			ValidationError("chart.metadata.name is required"),
 		},
+		{
+			"chart with dot name",
+			&Metadata{Name: ".", APIVersion: "v2", Version: "1.0"},
+			ValidationError("chart.metadata.name \".\" is not allowed"),
+		},
+		{
+			"chart with dotdot name",
+			&Metadata{Name: "..", APIVersion: "v2", Version: "1.0"},
+			ValidationError("chart.metadata.name \"..\" is not allowed"),
+		},
 		{
 			"chart without name",
 			&Metadata{Name: "../../test", APIVersion: "v2", Version: "1.0"},

pkg/chart/v2/util/expand.go+17 −0 modified

@@ -52,6 +52,17 @@ func Expand(dir string, r io.Reader) error {
 		return errors.New("chart name not specified")
 	}
 
+	// Reject chart names that are POSIX path dot-segments or dot-dot segments or contain path separators.
+	// A dot-segment name (e.g. ".") causes SecureJoin to resolve to the root
+	// directory and extraction then to write files directly into that extraction root
+	// instead of a per-chart subdirectory.
+	if chartName == "." || chartName == ".." {
+		return fmt.Errorf("chart name %q is not allowed", chartName)
+	}
+	if chartName != filepath.Base(chartName) {
+		return fmt.Errorf("chart name %q must not contain path separators", chartName)
+	}
+
 	// Find the base directory
 	// The directory needs to be cleaned prior to passing to SecureJoin or the location may end up
 	// being wrong or returning an error. This was introduced in v0.4.0.
@@ -61,6 +72,12 @@ func Expand(dir string, r io.Reader) error {
 		return err
 	}
 
+	// Defense-in-depth: the chart directory must be a subdirectory of dir,
+	// never dir itself.
+	if chartdir == dir {
+		return fmt.Errorf("chart name %q resolves to the extraction root", chartName)
+	}
+
 	// Copy all files verbatim. We don't parse these files because parsing can remove
 	// comments.
 	for _, file := range files {

pkg/chart/v2/util/expand_test.go+84 −0 modified

@@ -17,11 +17,73 @@ limitations under the License.
 package util
 
 import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
+// makeTestChartArchive builds a gzipped tar archive from the given sourceDir directory, file entries are prefixed with the given chartName
+func makeTestChartArchive(t *testing.T, chartName, sourceDir string) *bytes.Buffer {
+	t.Helper()
+
+	var result bytes.Buffer
+	gw := gzip.NewWriter(&result)
+	tw := tar.NewWriter(gw)
+
+	dir := os.DirFS(sourceDir)
+
+	writeFile := func(relPath string) {
+		t.Helper()
+		f, err := dir.Open(relPath)
+		require.NoError(t, err)
+
+		fStat, err := f.Stat()
+		require.NoError(t, err)
+
+		err = tw.WriteHeader(&tar.Header{
+			Name: filepath.Join(chartName, relPath),
+			Mode: int64(fStat.Mode()),
+			Size: fStat.Size(),
+		})
+		require.NoError(t, err)
+
+		data, err := fs.ReadFile(dir, relPath)
+		require.NoError(t, err)
+		tw.Write(data)
+	}
+
+	err := fs.WalkDir(dir, ".", func(path string, d os.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+
+		if d.IsDir() {
+			return nil
+		}
+
+		writeFile(path)
+
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = tw.Close()
+	require.NoError(t, err)
+	err = gw.Close()
+	require.NoError(t, err)
+
+	return &result
+}
+
 func TestExpand(t *testing.T) {
 	dest := t.TempDir()
 
@@ -75,6 +137,28 @@ func TestExpand(t *testing.T) {
 	}
 }
 
+func TestExpandError(t *testing.T) {
+	tests := map[string]struct {
+		chartName string
+		chartDir  string
+		wantErr   string
+	}{
+		"dot name":      {"dotname", "testdata/dotname", "not allowed"},
+		"dotdot name":   {"dotdotname", "testdata/dotdotname", "not allowed"},
+		"slash in name": {"slashinname", "testdata/slashinname", "must not contain path separators"},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			archive := makeTestChartArchive(t, tt.chartName, tt.chartDir)
+
+			dest := t.TempDir()
+			err := Expand(dest, archive)
+			assert.ErrorContains(t, err, tt.wantErr)
+		})
+	}
+}
+
 func TestExpandFile(t *testing.T) {
 	dest := t.TempDir()

pkg/chart/v2/util/testdata/dotdotname/Chart.yaml+4 −0 added

@@ -0,0 +1,4 @@
+apiVersion: v3
+name: ..
+description: A Helm chart for Kubernetes
+version: 0.1.0
\ No newline at end of file

pkg/chart/v2/util/testdata/dotname/Chart.yaml+4 −0 added

@@ -0,0 +1,4 @@
+apiVersion: v3
+name: .
+description: A Helm chart for Kubernetes
+version: 0.1.0
\ No newline at end of file

pkg/chart/v2/util/testdata/slashinname/Chart.yaml+4 −0 added

@@ -0,0 +1,4 @@
+apiVersion: v3
+name: a/../b
+description: A Helm chart for Kubernetes
+version: 0.1.0
\ No newline at end of file

Vulnerability mechanics

Generated by null/stub on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

github.com/helm/helm/commit/4e7994d4467182f535b6797c94b5b0e994a91436nvdPatchWEB
github.com/advisories/GHSA-hr2v-4r36-88hrghsaADVISORY
github.com/helm/helm/security/advisories/GHSA-hr2v-4r36-88hrnvdMitigationVendor AdvisoryWEB
nvd.nist.gov/vuln/detail/CVE-2026-35206ghsaADVISORY
github.com/helm/helm/releases/tag/v4.1.4nvdProductRelease NotesWEB

News mentions

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cvss	0.286
epss	0.000
exploit	0.000
kev	0.000
patch	-0.070
ransomware	0.000