Vulnerability-Lookup

CVE-2026-45021 (GCVE-0-2026-45021)

Vulnerability from cvelistv5 – Published: 2026-05-28 17:45 – Updated: 2026-05-28 19:30

Title

Kuma: Default kuma-cp leaks admin token cross-origin via CORS wildcard + LocalhostIsAdmin

Summary

Kuma is a modern Envoy-based service mesh that can run on every cloud across both Kubernetes and VMs. Prior to 2.7.25, 2.9.15, 2.11.13, 2.12.10, and 2.13.5, the default kuma-cp config leaks the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. CorsAllowedDomains: [".*"] reflects any Origin, and LocalhostIsAdmin: true promotes requests from 127.0.0.1 to mesh-system:admin. A cross-origin fetch() from a malicious page returns the admin JWT and signing material. This vulnerability is fixed in 2.7.25, 2.9.15, 2.11.13, 2.12.10, and 2.13.5.

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: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-28 19:30 UTC

CWE

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

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7637 records in the last 180 days details

References

8 references

URL	Tags
https://github.com/kumahq/kuma/security/advisorie…	x_refsource_CONFIRM
https://github.com/kumahq/kuma/pull/16416	x_refsource_MISC
https://github.com/kumahq/kuma/pull/16423	x_refsource_MISC
https://github.com/kumahq/kuma/pull/16424	x_refsource_MISC
https://github.com/kumahq/kuma/pull/16425	x_refsource_MISC
https://github.com/kumahq/kuma/pull/16426	x_refsource_MISC
https://github.com/kumahq/kuma/pull/16427	x_refsource_MISC
https://github.com/kumahq/kuma/commit/8fefa8595d4…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
kumahq	kuma	Affected: < 2.7.25 Affected: >= 2.9.0, < 2.9.15 Affected: >= 2.11.0, < 2.11.13 Affected: >= 2.12.0, < 2.12.10 Affected: >= 2.13.0, < 2.13.5	guessed

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}

FKIE_CVE-2026-45021

Vulnerability from fkie_nvd - Published: 2026-05-28 18:16 - Updated: 2026-06-17 10:51

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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/kumahq/kuma/commit/8fefa8595d44eb68d922405702ed7a0826322907
	security-advisories@github.com	https://github.com/kumahq/kuma/pull/16416
	security-advisories@github.com	https://github.com/kumahq/kuma/pull/16423
	security-advisories@github.com	https://github.com/kumahq/kuma/pull/16424
	security-advisories@github.com	https://github.com/kumahq/kuma/pull/16425
	security-advisories@github.com	https://github.com/kumahq/kuma/pull/16426
	security-advisories@github.com	https://github.com/kumahq/kuma/pull/16427
	security-advisories@github.com	https://github.com/kumahq/kuma/security/advisories/GHSA-3vcp-chfh-f6r2

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "kuma",
          "vendor": "kumahq",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.7.25"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.9.0, \u003c 2.9.15"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.11.0, \u003c 2.11.13"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.12.0, \u003c 2.12.10"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.13.0, \u003c 2.13.5"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Kuma is a modern Envoy-based service mesh that can run on every cloud across both Kubernetes and VMs. Prior to 2.7.25, 2.9.15, 2.11.13, 2.12.10, and 2.13.5, the default kuma-cp config leaks the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. CorsAllowedDomains: [\".*\"] reflects any Origin, and LocalhostIsAdmin: true promotes requests from 127.0.0.1 to mesh-system:admin. A cross-origin fetch() from a malicious page returns the admin JWT and signing material. This vulnerability is fixed in 2.7.25, 2.9.15, 2.11.13, 2.12.10, and 2.13.5."
    }
  ],
  "id": "CVE-2026-45021",
  "lastModified": "2026-06-17T10:51:36.840",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.1,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "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/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "LOW",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-45021",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-28T19:30:17.834875Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-28T18:16:34.167",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/commit/8fefa8595d44eb68d922405702ed7a0826322907"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/pull/16416"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/pull/16423"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/pull/16424"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/pull/16425"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/pull/16426"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/pull/16427"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/kumahq/kuma/security/advisories/GHSA-3vcp-chfh-f6r2"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-346"
        },
        {
          "lang": "en",
          "value": "CWE-942"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-3VCP-CHFH-F6R2

Vulnerability from github – Published: 2026-05-14 20:15 – Updated: 2026-06-09 10:19

Summary

Default kuma-cp leaks admin token cross-origin via CORS wildcard + LocalhostIsAdmin

Details

Summary

Default kuma-cp config leaks the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. CorsAllowedDomains: [".*"] reflects any Origin, and LocalhostIsAdmin: true promotes requests from 127.0.0.1 to mesh-system:admin. A cross-origin fetch() from a malicious page returns the admin JWT and signing material.

Am I affected?

You are affected if all of these hold:

kuma-cp runs with default config (CorsAllowedDomains: [".*"] and LocalhostIsAdmin: true).
The control plane is reachable from a browser on the same machine:
kuma-cp run on a developer laptop
Docker --network host or port-publish on a workstation
kubectl port-forward from a machine that also browses the web
The operator visits a page running attacker JavaScript while the control plane is reachable.

You are not affected if:

The control plane runs on a Kubernetes cluster accessed via ClusterIP, NodePort, or LoadBalancer from a remote client.
The control plane runs on an SSH-administered VM with no browser on the host.
KUMA_API_SERVER_AUTHN_LOCALHOST_IS_ADMIN=false is set (see https://kuma.io/docs/latest/production/secure-deployment/api-server-auth/).
KUMA_API_SERVER_CORS_ALLOWED_DOMAINS is set to an explicit allowlist that excludes attacker origins.

Mitigation

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, for example http://localhost:5681,http://127.0.0.1:5681.
Do not run kuma-cp on a machine where you browse untrusted sites.

Fix

Fixed in #16416, backported to all supported release branches (#16423, #16424, #16425, #16426, #16427).

Changes in patched versions:

CorsAllowedDomains default changed from [".*"] to [] — CORS is now opt-in; set the env var explicitly if you need GUI access.
LocalhostIsAdmin hardened: now requires direct loopback RemoteAddr and Host, and rejects requests carrying proxy-hop headers (X-Forwarded-For), cross-site fetch metadata (Sec-Fetch-Site), or a non-localhost Origin.

Upgrade to a patched version:

2.7.25
2.9.15
2.11.13
2.12.10
2.13.5

Credits

Reported by eldudareeno.

CVSS

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 = 5.1 Medium.

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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/kumahq/kuma"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.7.25"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/kumahq/kuma"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.9.0"
            },
            {
              "fixed": "2.9.15"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/kumahq/kuma"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.11.0"
            },
            {
              "fixed": "2.11.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/kumahq/kuma"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.12.0"
            },
            {
              "fixed": "2.12.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/kumahq/kuma"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.13.0"
            },
            {
              "fixed": "2.13.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45021"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346",
      "CWE-942"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-14T20:15:08Z",
    "nvd_published_at": "2026-05-28T18:16:34Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nDefault `kuma-cp` config leaks the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. `CorsAllowedDomains: [\".*\"]` reflects any `Origin`, and `LocalhostIsAdmin: true` promotes requests from `127.0.0.1` to `mesh-system:admin`. A cross-origin `fetch()` from a malicious page returns the admin JWT and signing material.\n\n## Am I affected?\n\nYou are affected if all of these hold:\n\n1. `kuma-cp` runs with default config (`CorsAllowedDomains: [\".*\"]` and `LocalhostIsAdmin: true`).\n2. The control plane is reachable from a browser on the same machine:\n   - `kuma-cp run` on a developer laptop\n   - Docker `--network host` or port-publish on a workstation\n   - `kubectl port-forward` from a machine that also browses the web\n3. The operator visits a page running attacker JavaScript while the control plane is reachable.\n\nYou are not affected if:\n\n- The control plane runs on a Kubernetes cluster accessed via 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 (see https://kuma.io/docs/latest/production/secure-deployment/api-server-auth/).\n- `KUMA_API_SERVER_CORS_ALLOWED_DOMAINS` is set to an explicit allowlist that excludes attacker origins.\n\n## Mitigation\n\n1. Set `KUMA_API_SERVER_AUTHN_LOCALHOST_IS_ADMIN=false` after retrieving the admin token.\n2. Set `KUMA_API_SERVER_CORS_ALLOWED_DOMAINS` to an explicit allowlist, for example `http://localhost:5681,http://127.0.0.1:5681`.\n3. Do not run `kuma-cp` on a machine where you browse untrusted sites.\n\n## Fix\n\nFixed in [#16416](https://github.com/kumahq/kuma/pull/16416), backported to all supported release branches ([#16423](https://github.com/kumahq/kuma/pull/16423), [#16424](https://github.com/kumahq/kuma/pull/16424), [#16425](https://github.com/kumahq/kuma/pull/16425), [#16426](https://github.com/kumahq/kuma/pull/16426), [#16427](https://github.com/kumahq/kuma/pull/16427)).\n\nChanges in patched versions:\n\n- `CorsAllowedDomains` default changed from `[\".*\"]` to `[]` \u2014 CORS is now opt-in; set the env var explicitly if you need GUI access.\n- `LocalhostIsAdmin` hardened: now requires direct loopback `RemoteAddr` and `Host`, and rejects requests carrying proxy-hop headers (`X-Forwarded-For`), cross-site fetch metadata (`Sec-Fetch-Site`), or a non-localhost `Origin`.\n\nUpgrade to a patched version:\n\n- 2.7.25\n- 2.9.15\n- 2.11.13\n- 2.12.10\n- 2.13.5\n\n## Credits\n\nReported by `eldudareeno`.\n\n## CVSS\n\n`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` = 5.1 Medium.",
  "id": "GHSA-3vcp-chfh-f6r2",
  "modified": "2026-06-09T10:19:22Z",
  "published": "2026-05-14T20:15:08Z",
  "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-2026-45021"
    },
    {
      "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://github.com/kumahq/kuma/commit/8fefa8595d44eb68d922405702ed7a0826322907"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/kumahq/kuma"
    }
  ],
  "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Default kuma-cp leaks admin token cross-origin via CORS wildcard + LocalhostIsAdmin"
}

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-45021 (GCVE-0-2026-45021)

FKIE_CVE-2026-45021

GHSA-3VCP-CHFH-F6R2

Summary

Am I affected?

Mitigation

Fix

Credits

CVSS

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour