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

Source: https://junglewise.ai/threats/cve-2026-18676-default-kuma-cp-leaks-admin-token-cross-origin-via-cors-wildcard  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-12  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/github-com-kumahq-kuma), [github.com/kumahq/kuma/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-kumahq-kuma-v2). Vendors: [Go](https://junglewise.ai/threats/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

  ```sh
  go get github.com/kumahq/kuma@v2.7.25
  ```

- github.com/kumahq/kuma/v2 (Go): upgrade to 2.13.5 or later

  ```sh
  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

## Related threats

- [kuma-dp connects to control plane without verifying TLS certificate when no CA is configured](https://junglewise.ai/threats/cve-2026-18679-kuma-dp-connects-to-control-plane-without-verifying-tls)
- [kumactl connects to control plane without verifying TLS certificate when no CA is configured](https://junglewise.ai/threats/cve-2026-18678-kumactl-connects-to-control-plane-without-verifying-tls)
- [github.com/kumahq/kuma affected by](https://junglewise.ai/threats/github-com-kumahq-kuma-affected-by-f5263b57)