4.8

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-35206

CVE-2026-35206: Helm Chart extraction output directory collapse via `Chart.yaml` name dot-segment

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.

(GitHub Advisory)

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CVE-2026-35206

CVE-2026-35206:

4.8

CVSS Score

4.0

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
helm.sh/helm/v4	go	<= 4.1.3	4.1.4
helm.sh/helm/v3	go	<= 3.20.1	3.20.2

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability is a path traversal issue in Helm's chart extraction process, triggered by a chart having a name of . or .. in its Chart.yaml file. When helm pull --untar is executed on such a chart, the Expand function is called. In vulnerable versions, this function did not sanitize the chart name before using it to construct the destination path for extraction. This resulted in the chart's contents being written to the parent directory, potentially overwriting existing files, instead of a new directory named after the chart.

The patch 4e7994d4467182f535b6797c94b5b0e994a91436 rectifies this by adding validation in two key locations. First, the Metadata.Validate method is updated to reject charts with these special names during the initial metadata parsing. Second, as a defense-in-depth measure, the Expand function itself now also checks for and disallows these names before proceeding with the extraction. Both v2 and v3 of the chart format were affected, and the fixes were applied to the corresponding packages (pkg/chart/v2 and internal/chart/v3). Therefore, the Expand and Metadata.Validate functions within these packages are the identified vulnerable functions.

Vulnerable functions

internal/chart/v3/util.Expand

internal/chart/v3/util/expand.go

This function is responsible for expanding the chart archive. Prior to the patch, it did not validate the chart name. A chart name of '.' or '..' would cause the files to be extracted into the parent directory instead of a dedicated subdirectory, leading to a path traversal vulnerability.

pkg/chart/v2/util.Expand

pkg/chart/v2/util/expand.go

This function is the equivalent of `internal/chart/v3/util.Expand` but for v2 charts. It shares the same vulnerability where a chart name of '.' or '..' is not properly handled, leading to path traversal during extraction.

internal/chart/v3.Metadata.Validate

internal/chart/v3/metadata.go

This method validates the chart's metadata from `Chart.yaml`. In vulnerable versions, it failed to check for '.' or '..' as chart names. This allowed a malicious chart to pass validation and be processed by the vulnerable `Expand` function.

pkg/chart/v2.Metadata.Validate

pkg/chart/v2/metadata.go

This method is the equivalent of `internal/chart/v3.Metadata.Validate` for v2 charts. It shares the same flaw of not validating against '.' or '..' in the chart name, thus contributing to the vulnerability.

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WAF Rule

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Reasoning

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