Helm's plugin verification fails open when .prov is missing, allowing unsigned plugin install

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.4 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-35205: 0.22% estimated exploitation activity in the next 30 days; percentile 12.28 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Helm is a package manager for Charts for Kubernetes. In Helm versions =4.0.0 and <=4.1.3, Helm will install plugins missing provenance (.prov file) when signature verification is required. Impact The bug allows plugin authors to omit provenance (signing) data from plugins, bypassing plugin signature verification upon plugin install/update. Notably, plugin hooks will be executed as designed on the installed plugin, enabling a malicious plugin to execute arbitrary code. Patches This issue has been patched in Helm v4.1.4 Installing/updating a plugin with missing provenance will error if signature verification is required. Workarounds Users may manually validate that a plugin archive is not missing provenance data (.prov file) before installation.

Published by the source

10 Apr 2026, 15:33 UTC

Last modified by the source

24 Apr 2026, 20:42 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-q5jf-9vfq-h4h7

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# Patch Next advisory brief: CVE-2026-35205

Advisory: Helm's plugin verification fails open when .prov is missing, allowing unsigned plugin install
IDs: CVE-2026-35205, GHSA-q5jf-9vfq-h4h7
Record: https://patchnext.com/advisories/cve-2026-35205 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: helm.sh/helm/v4 4.1.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go helm.sh/helm/v4: affected >= 4.0.0, <= 4.1.3; fixed in 4.1.4

## Suggested inspection (read-only)
- Go helm.sh/helm/v4: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on helm.sh/helm/v4.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-q5jf-9vfq-h4h7 (GitHub-reviewed advisory GHSA-q5jf-9vfq-h4h7 lists affected ranges: Go helm.sh/helm/v4 >=4.0.0 <=4.1.3)

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