CVE-2026-18676

Kong Mesh: default control plane config leaks the admin token cross-origin via a CORS wildcard and localhost admin

Published Aug 12, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

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.


Vendor Workaround

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.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Konghq
Konghq kong Mesh
Vendors & Products Konghq
Konghq kong Mesh
Type Values Removed Values Added
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.
Title Kong Mesh: default control plane config leaks the admin token cross-origin via a CORS wildcard and localhost admin
Weaknesses CWE-346
CWE-942
References
Metrics cvssV4_0

{'score': 5.1, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Kong
Published
Updated
Aug 13, 2026, 2:50 PM
Reserved
Aug 3, 2026, 3:20 PM
Status
Awaiting Analysis
Published
Aug 12, 2026, 7:17 PM
Modified
Oct 23, 2026, 7:10 PM