GHSA-MXXC-P822-2HX9

Vulnerability from github – Published: 2026-01-26 23:26 – Updated: 2026-01-26 23:26
VLAI?
Summary
Skipper Ingress Controller Allows Unauthorized Access to Internal Services via ExternalName
Details

Impact

When running Skipper as an Ingress controller, users with permissions to create an Ingress and a Service of type ExternalName can create routes that enable them to use Skipper's network access to reach internal services.

Patches

https://github.com/zalando/skipper/releases/tag/v0.24.0 disables Kubernetes ExternalName by default.

Workarounds

Developers can allow list targets of an ExternalName by using -kubernetes-only-allowed-external-names=true and allow list via regular expressions -kubernetes-allowed-external-name '^[a-z][a-z0-9-.]+[.].allowed.example$'

References

https://kubernetes.io/docs/concepts/services-networking/service/#externalname

Severity ?
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/zalando/skipper"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.24.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-24470"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-441",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-26T23:26:56Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\n\nWhen running Skipper as an Ingress controller, users with permissions to create an Ingress and a Service of type ExternalName can create routes that enable them to use Skipper\u0027s network access to reach internal services.\n\n### Patches\n\nhttps://github.com/zalando/skipper/releases/tag/v0.24.0 disables Kubernetes ExternalName by default.\n\n### Workarounds\n\nDevelopers can allow list targets of an ExternalName by using `-kubernetes-only-allowed-external-names=true` and allow list via regular expressions `-kubernetes-allowed-external-name \u0027^[a-z][a-z0-9-.]+[.].allowed.example$\u0027` \n\n### References\n\nhttps://kubernetes.io/docs/concepts/services-networking/service/#externalname",
  "id": "GHSA-mxxc-p822-2hx9",
  "modified": "2026-01-26T23:26:56Z",
  "published": "2026-01-26T23:26:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/zalando/skipper/security/advisories/GHSA-mxxc-p822-2hx9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zalando/skipper/commit/a4c87ce029a58eb8e1c2c1f93049194a39cf6219"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/zalando/skipper"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zalando/skipper/releases/tag/v0.24.0"
    },
    {
      "type": "WEB",
      "url": "https://kubernetes.io/docs/concepts/services-networking/service/#externalname"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Skipper Ingress Controller Allows Unauthorized Access to Internal Services via ExternalName"
}


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