Vulnerability-Lookup

GHSA-X23J-4PCQ-M26J

Vulnerability from github – Published: 2026-08-12 21:31 – Updated: 2026-08-12 21:31

Details

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.

Severity

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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-18676"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-12T19:17:30Z",
    "severity": "MODERATE"
  },
  "details": "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.\u00a0Due to a CORS misconfiguration a cross-origin fetch() from a malicious page returns the admin JWT and signing material.",
  "id": "GHSA-x23j-4pcq-m26j",
  "modified": "2026-08-12T21:31:37Z",
  "published": "2026-08-12T21:31:37Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/kumahq/kuma/security/advisories/GHSA-3vcp-chfh-f6r2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18676"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kumahq/kuma/pull/16416"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kumahq/kuma/pull/16423"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kumahq/kuma/pull/16424"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kumahq/kuma/pull/16425"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kumahq/kuma/pull/16426"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kumahq/kuma/pull/16427"
    },
    {
      "type": "WEB",
      "url": "https://developer.konghq.com/mesh/changelog"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-18676 (GCVE-0-2026-18676)

Vulnerability from cvelistv5 – Published: 2026-08-12 18:42 – Updated: 2026-08-13 14:50

Title

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

Summary

Severity

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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-13 14:50 UTC

CWE

CWE-346 - Origin Validation Error
CWE-942 - Permissive Cross-domain Policy with Untrusted Domain

Assigner

Kong mitre root

References

8 references

URL	Tags
https://github.com/kumahq/kuma/security/advisorie…	vendor-advisory
https://github.com/kumahq/kuma/pull/16416	patch
https://github.com/kumahq/kuma/pull/16423	patch
https://github.com/kumahq/kuma/pull/16424	patch
https://github.com/kumahq/kuma/pull/16425	patch
https://github.com/kumahq/kuma/pull/16426	patch
https://github.com/kumahq/kuma/pull/16427	patch
https://developer.konghq.com/mesh/changelog/	release-notes

Impacted products

1 product

Vendor	Product	Version
Kong Inc.	Kong Mesh	Affected: 0 , < 2.7.25 (semver) Affected: 2.8.0 , < 2.9.15 (semver) Affected: 2.10.0 , < 2.11.13 (semver) Affected: 2.12.0 , < 2.12.10 (semver) Affected: 2.13.0 , < 2.13.5 (semver)

Credits

eldudareeno

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-18676",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-13T14:50:34.609630Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-13T14:50:43.069Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "kuma-cp"
          ],
          "platforms": [
            "Linux"
          ],
          "product": "Kong Mesh",
          "vendor": "Kong Inc.",
          "versions": [
            {
              "lessThan": "2.7.25",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThan": "2.9.15",
              "status": "affected",
              "version": "2.8.0",
              "versionType": "semver"
            },
            {
              "lessThan": "2.11.13",
              "status": "affected",
              "version": "2.10.0",
              "versionType": "semver"
            },
            {
              "lessThan": "2.12.10",
              "status": "affected",
              "version": "2.12.0",
              "versionType": "semver"
            },
            {
              "lessThan": "2.13.5",
              "status": "affected",
              "version": "2.13.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eYou are affected if all of the following hold:\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003ccode\u003ekuma-cp\u003c/code\u003e runs with default config (\u003ccode\u003ecorsAllowedDomains: [\u0026quot;.*\u0026quot;]\u003c/code\u003e and \u003ccode\u003elocalhostIsAdmin: true\u003c/code\u003e).\u003c/li\u003e\u003cli\u003eThe control plane is reachable from a browser on the same machine: \u003ccode\u003ekuma-cp run\u003c/code\u003e on a developer laptop, Docker with host networking or a published port on a workstation, or \u003ccode\u003ekubectl port-forward\u003c/code\u003e from a machine that also browses the web.\u003c/li\u003e\u003cli\u003eThe operator visits a page running attacker JavaScript while the control plane is reachable.\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eYou are not affected if:\u003c/p\u003e\u003cul\u003e\u003cli\u003eThe control plane runs on a Kubernetes cluster accessed over ClusterIP, NodePort, or LoadBalancer from a remote client.\u003c/li\u003e\u003cli\u003eThe control plane runs on an SSH-administered VM with no browser on the host.\u003c/li\u003e\u003cli\u003e\u003ccode\u003eKUMA_API_SERVER_AUTHN_LOCALHOST_IS_ADMIN=false\u003c/code\u003e is set.\u003c/li\u003e\u003cli\u003e\u003ccode\u003eKUMA_API_SERVER_CORS_ALLOWED_DOMAINS\u003c/code\u003e is set to an explicit allowlist that excludes attacker origins.\u003c/li\u003e\u003c/ul\u003e"
            }
          ],
          "value": "You are affected if all of the following hold:\n\n  *  kuma-cp runs with default config (corsAllowedDomains: [\".*\"] and localhostIsAdmin: true).\n  *  The control plane is reachable from a browser on the same machine: kuma-cp run on a developer laptop, Docker with host networking or a published port on a workstation, or kubectl port-forward from a machine that also browses the web.\n  *  The operator visits a page running attacker JavaScript while the control plane is reachable.\n\n\n\n\nYou are not affected if:\n\n  *  The control plane runs on a Kubernetes cluster accessed over ClusterIP, NodePort, or LoadBalancer from a remote client.\n  *  The control plane runs on an SSH-administered VM with no browser on the host.\n  *  KUMA_API_SERVER_AUTHN_LOCALHOST_IS_ADMIN=false is set.\n  *  KUMA_API_SERVER_CORS_ALLOWED_DOMAINS is set to an explicit allowlist that excludes attacker origins."
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "eldudareeno"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eThe default \u003ccode\u003ekuma-cp\u003c/code\u003e 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.\u0026nbsp;Due to a CORS misconfiguration a cross-origin \u003ccode\u003efetch()\u003c/code\u003e from a malicious page returns the admin JWT and signing material.\u003c/p\u003e"
            }
          ],
          "value": "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.\u00a0Due to a CORS misconfiguration a cross-origin fetch() from a malicious page returns the admin JWT and signing material."
        }
      ],
      "impacts": [
        {
          "descriptions": [
            {
              "lang": "en",
              "value": "Credential disclosure"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.1,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "ACTIVE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-346",
              "description": "CWE-346 Origin Validation Error",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-942",
              "description": "CWE-942 Permissive Cross-domain Policy with Untrusted Domain",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-12T18:43:32.594Z",
        "orgId": "02762ae7-200e-4b20-9b2b-a77d5b8fc4cb",
        "shortName": "Kong"
      },
      "references": [
        {
          "name": "Upstream advisory GHSA-3vcp-chfh-f6r2",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/kumahq/kuma/security/advisories/GHSA-3vcp-chfh-f6r2"
        },
        {
          "name": "kumahq/kuma#16416 (master)",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/kumahq/kuma/pull/16416"
        },
        {
          "name": "kumahq/kuma#16423 (backport)",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/kumahq/kuma/pull/16423"
        },
        {
          "name": "kumahq/kuma#16424 (backport)",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/kumahq/kuma/pull/16424"
        },
        {
          "name": "kumahq/kuma#16425 (backport)",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/kumahq/kuma/pull/16425"
        },
        {
          "name": "kumahq/kuma#16426 (backport)",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/kumahq/kuma/pull/16426"
        },
        {
          "name": "kumahq/kuma#16427 (backport)",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/kumahq/kuma/pull/16427"
        },
        {
          "name": "Kong MESH Changelog",
          "tags": [
            "release-notes"
          ],
          "url": "https://developer.konghq.com/mesh/changelog/"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eUpgrade 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 \u003ccode\u003ecorsAllowedDomains\u003c/code\u003e default changed from \u003ccode\u003e[\u0026quot;.*\u0026quot;]\u003c/code\u003e to \u003ccode\u003e[]\u003c/code\u003e, making CORS opt-in, and \u003ccode\u003elocalhostIsAdmin\u003c/code\u003e was hardened to require a direct loopback \u003ccode\u003eRemoteAddr\u003c/code\u003e and \u003ccode\u003eHost\u003c/code\u003e and to reject requests carrying proxy-hop headers (\u003ccode\u003eX-Forwarded-For\u003c/code\u003e), cross-site fetch metadata (\u003ccode\u003eSec-Fetch-Site\u003c/code\u003e), or a non-localhost \u003ccode\u003eOrigin\u003c/code\u003e. The 2.14 line shipped after the fix and was never affected.\u003c/p\u003e"
            }
          ],
          "value": "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."
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "timeline": [
        {
          "lang": "en",
          "time": "2026-05-01T07:01:00.000Z",
          "value": "Kong Mesh patched releases published"
        },
        {
          "lang": "en",
          "time": "2026-05-09T06:15:00.000Z",
          "value": "Upstream advisory GHSA-3vcp-chfh-f6r2 published"
        }
      ],
      "title": "Kong Mesh: default control plane config leaks the admin token cross-origin via a CORS wildcard and localhost admin",
      "workarounds": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eSet \u003ccode\u003eKUMA_API_SERVER_AUTHN_LOCALHOST_IS_ADMIN=false\u003c/code\u003e after retrieving the admin token, set \u003ccode\u003eKUMA_API_SERVER_CORS_ALLOWED_DOMAINS\u003c/code\u003e to an explicit allowlist such as \u003ccode\u003ehttp://localhost:5681,http://127.0.0.1:5681\u003c/code\u003e, and do not run \u003ccode\u003ekuma-cp\u003c/code\u003e on a machine used to browse untrusted sites.\u003c/p\u003e"
            }
          ],
          "value": "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."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "02762ae7-200e-4b20-9b2b-a77d5b8fc4cb",
    "assignerShortName": "Kong",
    "cveId": "CVE-2026-18676",
    "datePublished": "2026-08-12T18:42:38.843Z",
    "dateReserved": "2026-08-03T15:20:44.526Z",
    "dateUpdated": "2026-08-13T14:50:43.069Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-X23J-4PCQ-M26J

CVE-2026-18676 (GCVE-0-2026-18676)

Tags

Sightings

Nomenclature

Related by attack behaviour