CVE-2026-35205: Helm.sh/helm/v4 Helm's Plugin Verification Fails Open Vulnerability

HIGH
Advisory Identifier: GHSA-q5jf-9vfq-h4h7
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CVSS 7.8
CWE-636
Published
Advisory Summary

CVE-2026-35205 is a HIGH (CVSS 7.8) helm's plugin verification fails open vulnerability (CWE-636: Not Failing Securely ('Failing Open')) affecting Helm.sh/helm/v4 libraries in the Go ecosystem. The issue involves helm's plugin verification fails open when .prov is missing, allowing unsigned plugin install. Remediation is available by upgrading affected packages to version 4.1.4.

CVE-2026-35205 at a Glance

CVE Identifier CVE-2026-35205
GHSA Identifier GHSA-q5jf-9vfq-h4h7
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification CWE-636: Not Failing Securely ('Failing Open')
Affected Product Helm.sh/helm/v4
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 7.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-35205

To remediate this vulnerability, upgrade all affected Helm.sh/helm/v4 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

helm.sh/helm/v4 fixed: 4.1.4 
Upgrade helm.sh/helm/v4 to 4.1.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for helm.sh/helm/v4

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-35205, inspect your project dependencies for Helm.sh/helm/v4:

inspect dependencies for helm.sh/helm/v4

Analyze the terminal output to locate any version of Helm.sh/helm/v4 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.1.4), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-636: Not Failing Securely ('Failing Open'), where when the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions. In Helm.sh/helm/v4, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-35205 Affected Helm.sh/helm/v4 Versions

1 component(s)
Fixed Versions:
4.1.4
Product / Package Ecosystem Affected Versions Fixed Version
helm.sh/helm/v4
golang/helm.sh/helm/v4
Go
≥ 4.0.0
< 4.1.4
4.1.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/helm/helm/security/advisories/GHSA-q5jf-9vfq-h4h7
NVD — CVE-2026-35205 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-35205
Security Fix Commit FIX COMMIT
https://github.com/helm/helm/commit/05fa37973dc9e42b76e1d2883494c87174b6074f
Helm.sh/helm/v4 Source Repository REPOSITORY
https://github.com/helm/helm
Helm.sh/helm/v4 Release RELEASE
https://github.com/helm/helm/releases/tag/v4.1.4
helm.sh/docs/topics/provena... WEB
https://helm.sh/docs/topics/provenance/#the-provenance-file

Frequently Asked Questions

What is CVE-2026-35205?
CVE-2026-35205 is a security vulnerability in Helm.sh/helm/v4 involving Helm's plugin verification fails open when .prov is missing, allowing unsigned plugin install under CWE-636: Not Failing Securely ('Failing Open').
Which Helm.sh/helm/v4 versions are affected?
Affected versions include releases prior to 4.1.4 across affected packages: helm.sh/helm/v4.
What version fixes CVE-2026-35205?
Upgrading to 4.1.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is helm.sh/helm/v4 affected?
Yes, helm.sh/helm/v4 is affected in releases prior to 4.1.4. Upgrade your dependency to 4.1.4 or later.
What is the CVSS score of CVE-2026-35205?
CVE-2026-35205 has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-35205?
CVE-2026-35205 is classified under CWE-636: Not Failing Securely ('Failing Open') (When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.).
How can I check Go dependencies for CVE-2026-35205?
Run the dependency tree command: 'inspect dependencies for helm.sh/helm/v4'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q5jf-9vfq-h4h7",
  "modified" : "2026-04-24T20:42:00Z",
  "published" : "2026-04-10T15:33:03Z",
  "aliases" : [ "CVE-2026-35205" ],
  "summary" : "Helm's plugin verification fails open when .prov is missing, allowing unsigned plugin install",
  "details" : "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.\n\n### Impact\n\nThe bug allows plugin authors to omit provenance (signing) data from plugins, bypassing plugin signature verification upon plugin install/update.\n\nNotably, plugin hooks will be executed as designed on the installed plugin, enabling a malicious plugin to execute arbitrary code.\n\n### Patches\n\nThis issue has been patched in Helm v4.1.4\n\nInstalling/updating a plugin with missing provenance will error if signature verification is required.\n\n### Workarounds\n\nUsers may manually validate that a plugin archive is not missing provenance data (`.prov` file) before installation.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "helm.sh/helm/v4"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.1.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/helm/helm/security/advisories/GHSA-q5jf-9vfq-h4h7"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-35205"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/helm/helm/commit/05fa37973dc9e42b76e1d2883494c87174b6074f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/helm/helm"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/helm/helm/releases/tag/v4.1.4"
  }, {
    "type" : "WEB",
    "url" : "https://helm.sh/docs/topics/provenance/#the-provenance-file"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-636" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-10T15:33:03Z",
    "nvd_published_at" : "2026-04-09T16:16:27Z"
  }
}