CVE-2020-8562 (GCVE-0-2020-8562)

Vulnerability from cvelistv5 – Published: 2022-02-01 10:33 – Updated: 2026-06-01 21:45
VLAI
Title
Bypass of Kubernetes API Server proxy TOCTOU
Summary
As mitigations to a report from 2019 and CVE-2020-8555, Kubernetes attempts to prevent proxied connections from accessing link-local or localhost networks when making user-driven connections to Services, Pods, Nodes, or StorageClass service providers. As part of this mitigation Kubernetes does a DNS name resolution check and validates that response IPs are not in the link-local (169.254.0.0/16) or localhost (127.0.0.0/8) range. Kubernetes then performs a second DNS resolution without validation for the actual connection. If a non-standard DNS server returns different non-cached responses, a user may be able to bypass the proxy IP restriction and access private networks on the control plane.
Severity
2.2 (Low)
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N
CWE
  • CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
Assigner
References
Impacted products
Vendor Product Version
Kubernetes Kubernetes Affected: 0 , < * (semver)
Create a notification for this product.
Date Public
2021-05-04 00:00
Credits
Javier Provecho
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-04T10:03:46.172Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
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        "references": [
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            ],
            "url": "https://github.com/kubernetes/kubernetes/issues/101493"
          },
          {
            "tags": [
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              "x_transferred"
            ],
            "url": "https://groups.google.com/g/kubernetes-security-announce/c/-MFX60_wdOY"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://security.netapp.com/advisory/ntap-20220225-0002/"
          }
        ],
        "title": "CVE Program Container"
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    "cna": {
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          "vendor": "Kubernetes",
          "versions": [
            {
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              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Javier Provecho"
        }
      ],
      "datePublic": "2021-05-04T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "As mitigations to a report from 2019 and CVE-2020-8555, Kubernetes attempts to prevent proxied connections from accessing link-local or localhost networks when making user-driven connections to Services, Pods, Nodes, or StorageClass service providers. As part of this mitigation Kubernetes does a DNS name resolution check and validates that response IPs are not in the link-local (169.254.0.0/16) or localhost (127.0.0.0/8) range. Kubernetes then performs a second DNS resolution without validation for the actual connection. If a non-standard DNS server returns different non-cached responses, a user may be able to bypass the proxy IP restriction and access private networks on the control plane."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 2.2,
            "baseSeverity": "LOW",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "HIGH",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-367",
              "description": "CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-01T21:45:40.339Z",
        "orgId": "a6081bf6-c852-4425-ad4f-a67919267565",
        "shortName": "kubernetes"
      },
      "references": [
        {
          "tags": [
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          "url": "https://kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/"
        },
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          "url": "https://github.com/kubernetes/kubernetes/issues/101493"
        },
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        },
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          "url": "https://security.netapp.com/advisory/ntap-20220225-0002/"
        }
      ],
      "source": {
        "defect": [
          "https://github.com/kubernetes/kubernetes/issues/101493"
        ],
        "discovery": "EXTERNAL"
      },
      "title": "Bypass of Kubernetes API Server proxy TOCTOU",
      "workarounds": [
        {
          "lang": "en",
          "value": "If this issue affects your clusters\u2019 control planes, you can use dnsmasq for name resolution and configure the min-cache-ttl and neg-ttl parameters to a low non-zero value to enforce cached replies for proxied connections"
        }
      ],
      "x_generator": {
        "engine": "Vulnogram 0.0.9"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a6081bf6-c852-4425-ad4f-a67919267565",
    "assignerShortName": "kubernetes",
    "cveId": "CVE-2020-8562",
    "datePublished": "2022-02-01T10:33:00.317Z",
    "dateReserved": "2020-02-03T00:00:00.000Z",
    "dateUpdated": "2026-06-01T21:45:40.339Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2020-8562",
      "date": "2026-10-03",
      "epss": "0.01082",
      "percentile": "0.63971"
    }
  }
}



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