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Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-42457

CRITICAL · 9.0 CVSS v3.1 Published 2026-05-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
vCluster Platform provides a Kubernetes platform for managing virtual clusters, multi-tenancy, and cluster sharing. Prior to 4.4.3, 4.5.5, 4.6.2, 4.7.1, and 4.8.0, there is a Stored XSS attack vulnerability via the name field of a templateRef. This can lead to the execution of arbitrary external scripts within the platform's browser context. In the worst case, a malicious user could potentially create a new Global-Admin user, bypassing other security restrictions. The attacker needs the ability to create namespaces. This vulnerability is fixed in 4.4.3, 4.5.5, 4.6.2, 4.7.1, and 4.8.0.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A Stored XSS vulnerability in vCluster Platform allows malicious script injection via the name field of a templateRef. When users view the affected template in the browser context, the injected script executes, enabling session hijacking and potential privilege escalation to Global-Admin user creation.

MitigationUpgrade vCluster Platform to versions 4.4.3, 4.5.5, 4.6.2, 4.7.1, or 4.8.0 and later. Until patched, restrict or audit namespace creation permissions to limit the attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check vCluster Platform version
    Access the vCluster Platform admin UI or run 'vcluster platform version' CLI command to identify the installed version
    Affected if Version is 4.4.0-4.4.2, 4.5.0-4.5.4, 4.6.0-4.6.1, 4.7.0-4.7.0, or 4.8.0 before the fixed release
  2. Identify templateRef configurations
    Query the vCluster Platform API or check YAML configurations for resources containing 'templateRef' definitions, typically in virtual cluster template manifests
    Affected if templateRef resources exist in the environment
  3. Inspect templateRef name fields for XSS payloads
    Examine the 'name' field values within templateRef configurations for suspicious characters such as <script>, javascript:, onerror=, or HTML tags
    Affected if Any templateRef name field contains unescaped HTML/JavaScript syntax
  4. Audit recent template modifications
    Review template creation and modification logs or audit trails for unexpected changes to templateRef name fields
    Affected if Templates were recently modified with unusual name field content

You are affected if running a vulnerable vCluster Platform version AND templateRef resources with malicious name field content exist in your environment, which could enable session hijacking and privilege escalation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade vCluster Platform to versions 4.4.3, 4.5.5, 4.6.2, 4.7.1, or 4.8.0 and later. Until patched, restrict or audit namespace creation permissions to limit the attack surface.

Recommended fix High confidence

4.8.0 (or 4.4.3, 4.5.5, 4.6.2, or 4.7.1 depending on current version and compatibility needs)

  1. Check the current vCluster Platform version by accessing the platform's admin interface or running the appropriate CLI command
  2. Review the upgrade documentation for vCluster Platform to understand the upgrade process
  3. Plan the upgrade, ensuring to backup all critical data and configurations
  4. Upgrade vCluster Platform to version 4.8.0 (or alternatively to 4.4.3, 4.5.5, 4.6.2, or 4.7.1 depending on compatibility requirements)
  5. After upgrade, verify that the XSS vulnerability in the templateRef name field is patched by attempting to create a templateRef with a script tag in the name field (this should be sanitized/blocked)
  6. Verify that all platform functionality works correctly post-upgrade
  7. Review user permissions and audit logs to ensure no unauthorized access occurred during the vulnerability window

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,570
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42457 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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