# CVE-2026-35205: Helm signature verification bypass for plugins missing provenance files

Source: https://junglewise.ai/threats/cve-2026-35205-helm-signature-verification-bypass-for-plugins-missing-provenance  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-09. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-35205 · Severity: high · CVSS 7.8 · Published 2026-04-09

Helm, a popular package manager for Kubernetes, contains a security flaw where it fails to properly verify the digital signatures of plugins. If a user is tricked into installing a malicious plugin that is missing its security verification file, Helm will proceed with the installation even when signature verification is required. This could allow an attacker to execute unauthorized code on the user's system through plugin hooks.

Technologies: [helm.sh/helm/v4 (Go)](https://junglewise.ai/threats/technologies/helm-sh-helm-v4), [Helm](https://junglewise.ai/threats/technologies/helm). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Helm](https://junglewise.ai/threats/vendors/helm).

## Quick answers

**Is CVE-2026-35205 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-35205 being exploited in the wild.

**How severe is CVE-2026-35205?** High severity, with a CVSS score of 7.8, published 9 April 2026.

**Which products and versions are affected?** helm.sh/helm/v4 (Go) >= 4.0.0, <= 4.1.3, SEMVER:introduced=4.0.0,fixed=4.1.4; Helm >= 4.0.0, < 4.1.4.

**Is there a fix for CVE-2026-35205?** Yes. helm.sh/helm/v4 (Go): upgrade to 4.1.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-35205 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-35205?** Check whether you run helm.sh/helm/v4 (Go) or Helm at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- helm.sh/helm/v4 (Go): upgrade to 4.1.4 or later

  ```sh
  go get helm.sh/helm/v4@v4.1.4
  ```


## Technical details

A 'fail-open' vulnerability exists in Helm's plugin installer (internal/plugin/installer/installer.go) for versions 4.0.0 through 4.1.3. When signature verification is explicitly required during a plugin installation or update, Helm fails to error out if the provenance (.prov) file is entirely absent. An attacker can exploit this by providing a malicious plugin archive without a provenance file, bypassing the cryptographic integrity checks. If a user installs such a plugin, malicious plugin hooks can execute arbitrary code with the privileges of the Helm process. The issue is resolved in version 4.1.4 by ensuring the installer returns an error when provenance data is missing during a verified install.

## Affected products

- Helm Helm >= 4.0.0, < 4.1.4

## Identifiers

- CVE-2026-35205
- GHSA-q5jf-9vfq-h4h7
- GO-2026-5566

## Timeline

- 2026-04-09: disclosed
- 2026-04-09: patched: Fixed in version 4.1.4
- 2026-04-09: advisory

## References

- [https://github.com/helm/helm/commit/05fa37973dc9e42b76e1d2883494c87174b6074f](https://github.com/helm/helm/commit/05fa37973dc9e42b76e1d2883494c87174b6074f)
- [https://github.com/helm/helm/releases/tag/v4.1.4](https://github.com/helm/helm/releases/tag/v4.1.4)
- [https://github.com/helm/helm/security/advisories/GHSA-q5jf-9vfq-h4h7](https://github.com/helm/helm/security/advisories/GHSA-q5jf-9vfq-h4h7)
- [https://helm.sh/docs/topics/provenance/](https://helm.sh/docs/topics/provenance/)
- [https://access.redhat.com/errata/RHSA-2026:26441](https://access.redhat.com/errata/RHSA-2026:26441)
- [https://access.redhat.com/security/cve/CVE-2026-35205](https://access.redhat.com/security/cve/CVE-2026-35205)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2456927](https://bugzilla.redhat.com/show_bug.cgi?id=2456927)

## Related threats

- [Helm denial of service in Files.Lines template helper](https://junglewise.ai/threats/cve-2026-63308-helm-denial-of-service-in-files-lines-template-helper)
- [Helm path traversal via Chart.yaml name dot-segment](https://junglewise.ai/threats/cve-2026-35206-helm-path-traversal-via-chart-yaml-name-dot-segment)
- [Helm path traversal in plugin metadata version field](https://junglewise.ai/threats/cve-2026-35204-helm-path-traversal-in-plugin-metadata-version-field)