Kong Mesh: default control plane config leaks the admin token cross-origin via a CORS wildcard and localhost admin
Summary
| CVE | CVE-2026-18676 |
|---|---|
| State | PUBLISHED |
| Assigner | Kong |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-12 19:17:30 UTC |
| Updated | 2026-08-13 15:19:35 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 5.1 MEDIUM from 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.002300000 probability, percentile 0.139880000 (date 2026-08-14)
Problem Types: CWE-346 | CWE-942 | CWE-346 CWE-346 Origin Validation Error | CWE-942 CWE-942 Permissive Cross-domain Policy with Untrusted Domain
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | Secondary | 5.1 | MEDIUM | 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/E:X/C... |
| 4.0 | CNA | CVSS | 5.1 | MEDIUM | 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 |
CVSS v4.0 Breakdown
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Kong Inc. | Kong Mesh | affected 2.7.25 semver | Linux |
| CNA | Kong Inc. | Kong Mesh | affected 2.8.0 2.9.15 semver | Linux |
| CNA | Kong Inc. | Kong Mesh | affected 2.10.0 2.11.13 semver | Linux |
| CNA | Kong Inc. | Kong Mesh | affected 2.12.0 2.12.10 semver | Linux |
| CNA | Kong Inc. | Kong Mesh | affected 2.13.0 2.13.5 semver | Linux |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/kumahq/kuma/pull/16427 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | github.com | |
| github.com/kumahq/kuma/security/advisories/GHSA-3vcp-chfh-f6r2 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | github.com | |
| github.com/kumahq/kuma/pull/16423 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | github.com | |
| github.com/kumahq/kuma/pull/16426 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | github.com | |
| developer.konghq.com/mesh/changelog | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | developer.konghq.com | |
| github.com/kumahq/kuma/pull/16424 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | github.com | |
| github.com/kumahq/kuma/pull/16425 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | github.com | |
| github.com/kumahq/kuma/pull/16416 | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: eldudareeno (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-05-01T07:01:00.000Z | Kong Mesh patched releases published |
| CNA | 2026-05-09T06:15:00.000Z | Upstream advisory GHSA-3vcp-chfh-f6r2 published |
Solutions
CNA: Upgrade to Kong Mesh 2.7.25, 2.9.15, 2.11.13, 2.12.10 or 2.13.5, whichever matches your release line. In patched versions the corsAllowedDomains default changed from [".*"] to [], making CORS opt-in, and localhostIsAdmin was hardened to require a direct loopback RemoteAddr and Host and to reject requests carrying proxy-hop headers (X-Forwarded-For), cross-site fetch metadata (Sec-Fetch-Site), or a non-localhost Origin. The 2.14 line shipped after the fix and was never affected.
Workarounds
CNA: Set KUMA_API_SERVER_AUTHN_LOCALHOST_IS_ADMIN=false after retrieving the admin token, set KUMA_API_SERVER_CORS_ALLOWED_DOMAINS to an explicit allowlist such as http://localhost:5681,http://127.0.0.1:5681, and do not run kuma-cp on a machine used to browse untrusted sites.