CVE-2026-18675 — Kong Mesh: control plane denial of service via a malformed dataplane token with a non-string JWT kid
The dataplane token validator in kuma-cp performs an unchecked Go type assertion on the JWT kid header. A token whose kid is a JSON number decodes as a float64 and triggers a runtime panic before any signature, claims, or authorization check runs. The panic terminates the entire kuma-cp process, HTTP API, the health and readiness endpoints, and xDS. Unauthenticated access to the dataplane gRPC server can trigger the crash with a malformed token A single request is a transient interruption; sustaining an outage requires repeated requests.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.6% (30-day exploitation probability)+7
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Kong Kong Mesh).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 5.3 | CVSS 4.0 | Medium | — | — | 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb via NIST National Vulnerability Database |
| 5.3 | CVSS 4.0 | Medium | — | — | Kong via CVE Program (cve.org) e CISA ADP |
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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 (score shown at the top: 02762ae7-200e-4b20-9b2b-a77d5b8fc4cb) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Not enough vector or weakness data: use the affected application’s logs as a starting point.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · kong inc./kong mesh
- SSVC assessment updated
- Record published
- CVSS changed · 5.3
- Source status changed · → Awaiting Analysis
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
9 on the record
- github.com/kumahq/kuma/pull/17469
- github.com/kumahq/kuma/pull/17470
- github.com/kumahq/kuma/pull/17465
- github.com/kumahq/kuma/pull/17467
- github.com/kumahq/kuma/pull/17472
- github.com/kumahq/kuma/pull/17468
- github.com/kumahq/kuma/pull/17471
- developer.konghq.com/mesh/changelog/
- github.com/kumahq/kuma/security/advisories/GHSA-5mxq-7xq4-3vx8
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-18674 Kong Mesh multi-zone: the global control plane attributes KDS-synced resources by an unvalidated in-band zone identifier Aug 17, 2026
- Medium CVE-2026-18679 Kong Mesh: kuma-dp connects to the control plane without verifying the TLS certificate when no CA is configured Aug 12, 2026
- Medium CVE-2026-18677 Kong Mesh: a dataplane token without a workload binding can claim any workload's SPIFFE identity Aug 12, 2026
- Medium CVE-2026-18678 Kong Mesh: kumactl connects to the control plane without verifying the TLS certificate when no CA is configured Aug 12, 2026
- Medium CVE-2026-18673 Kong Mesh: the kuma-dp readiness service exposes the Envoy admin API without authentication Aug 12, 2026
- Medium CVE-2026-18676 Kong Mesh: default control plane config leaks the admin token cross-origin via a CORS wildcard and localhost admin Aug 12, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-18675 is "Kong Mesh: control plane denial of service via a malformed dataplane token with a non-string JWT kid", rated Medium. It affects Kong Mesh (Kong); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.56% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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