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Medium, CVSS 5.1

Default kuma-cp leaks admin token cross-origin via CORS wildcard + LocalhostIsAdmin

CVE-2026-45021GHSA-3vcp-chfh-f6r2

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/kumahq/kuma 2.13.5, 2.12.10, 2.11.13, 2.9.15, 2.7.25), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/kumahq/kuma

    Affected
    < 2.7.25>= 2.9.0, < 2.9.15>= 2.11.0, < 2.11.13>= 2.12.0, < 2.12.10>= 2.13.0, < 2.13.5
    Fixed in
    2.9.15, 2.7.25, 2.11.13, 2.12.10, 2.13.5

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
5.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-45021: 0.28% estimated exploitation activity in the next 30 days; percentile 20.09 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Default kuma-cp config leaks the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. CorsAllowedDomains: ["."] reflects any Origin, and LocalhostIsAdmin: true promotes requests from 127.0.0.1 to mesh-system:admin. A cross-origin fetch() from a malicious page returns the admin JWT and signing material. Am I affected? You are affected if all of these hold: 1. kuma-cp runs with default config (CorsAllowedDomains: ["."] and LocalhostIsAdmin: true). 2. The control plane is reachable from a browser on the same machine: - kuma-cp run on a developer laptop - Docker --network host or port-publish on a workstation - kubectl port-forward from a machine that also browses the web 3. The operator visits a page running attacker JavaScript while the control plane is reachable. You are not affected if: - The control plane runs on a Kubernetes cluster accessed via ClusterIP, NodePort, or LoadBalancer from a remote…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-3vcp-chfh-f6r2

Agent brief

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# Patch Next advisory brief: CVE-2026-45021

Advisory: Default kuma-cp leaks admin token cross-origin via CORS wildcard + LocalhostIsAdmin
IDs: CVE-2026-45021, GHSA-3vcp-chfh-f6r2
Record: https://patchnext.com/advisories/cve-2026-45021 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/kumahq/kuma 2.13.5, 2.12.10, 2.11.13, 2.9.15, 2.7.25. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/kumahq/kuma: affected < 2.7.25; >= 2.9.0, < 2.9.15; >= 2.11.0, < 2.11.13; >= 2.12.0, < 2.12.10; >= 2.13.0, < 2.13.5; fixed in 2.9.15, 2.7.25, 2.11.13, 2.12.10, 2.13.5

## Suggested inspection (read-only)
- Go github.com/kumahq/kuma: 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 github.com/kumahq/kuma.
- 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-3vcp-chfh-f6r2 (GitHub-reviewed advisory GHSA-3vcp-chfh-f6r2 lists affected ranges: Go github.com/kumahq/kuma >=0 =2.9.0 =2.11.0 =2.12.0 =2.13.0 <2.13.5)

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