CVE-2026-18676: GO-2026-5102 - Default kuma-cp leaks admin token cross-origin via CORS wildcard + LocalhostIsAdmin in github.com/kumahq/kuma

CVE-2026-18676 · Severity: medium · CVSS 4 · Published 2026-08-12

The default kuma-cp configuration in Kong Mesh reveals the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. Due to a CORS misconfiguration a cross-origin fetch() from a malicious page returns the admin JWT and signing material.

Technologies: github.com/kumahq/kuma (Go), github.com/kumahq/kuma/v2 (Go). Vendors: Go.

Quick answers

Is CVE-2026-18676 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-18676 being exploited in the wild.
How severe is CVE-2026-18676?
Medium severity, with a CVSS score of 4, published 12 August 2026.
Which products and versions are affected?
github.com/kumahq/kuma (Go) SEMVER:introduced=0, SEMVER:introduced=0,fixed=2.7.25; github.com/kumahq/kuma/v2 (Go) SEMVER:introduced=0,fixed=2.7.25,introduced=2.9.13,fixed=2.11.13,introduced=2.12.4,fixed=2.12.10,introduced=2.13.0,fixed=2.13.5.
Is there a fix for CVE-2026-18676?
Yes. github.com/kumahq/kuma (Go): upgrade to 2.7.25 or later; github.com/kumahq/kuma/v2 (Go): upgrade to 2.13.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-18676?
Check whether you run github.com/kumahq/kuma (Go) or github.com/kumahq/kuma/v2 (Go) 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

  • github.com/kumahq/kuma (Go): upgrade to 2.7.25 or later
    go get github.com/kumahq/kuma@v2.7.25
  • github.com/kumahq/kuma/v2 (Go): upgrade to 2.13.5 or later
    go get github.com/kumahq/kuma/v2@v2.13.5

Affected products

  • github.com/kumahq/kuma (Go) SEMVER:introduced=0, SEMVER:introduced=0,fixed=2.7.25
  • github.com/kumahq/kuma/v2 (Go) SEMVER:introduced=0,fixed=2.7.25,introduced=2.9.13,fixed=2.11.13,introduced=2.12.4,fixed=2.12.10,introduced=2.13.0,fixed=2.13.5

Identifiers

  • CVE-2026-18676
  • CVE-2026-45021
  • GHSA-3vcp-chfh-f6r2
  • GO-2026-5102

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