{"id":"CVE-2020-8562","state":"PUBLISHED","title":"Bypass of Kubernetes API Server proxy TOCTOU","description":"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.","publishedAt":"2022-02-01T10:33:00.317Z","updatedAt":"2026-06-01T21:45:40.339Z","severity":{"score":2.2,"label":"Low","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N","source":"kubernetes"},"assigner":"kubernetes","products":["Kubernetes Kubernetes"],"affected":[{"vendor":"Kubernetes","product":"Kubernetes","versions":[{"version":"0","status":"affected","lessThan":"*","versionType":"semver"}]}],"references":["https://kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/","https://github.com/kubernetes/kubernetes/issues/101493","https://groups.google.com/g/kubernetes-security-announce/c/-MFX60_wdOY","https://security.netapp.com/advisory/ntap-20220225-0002/"],"weaknesses":["CWE-367"],"ingestedAt":"2026-10-29T19:47:44.297Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2020/8xxx/CVE-2020-8562.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2020-8562","state":"PUBLISHED","datePublished":"2022-02-01T10:33:00.317Z","dateUpdated":"2026-06-01T21:45:40.339Z","assignerShortName":"kubernetes","assignerOrgId":"a6081bf6-c852-4425-ad4f-a67919267565","dateReserved":"2020-02-03T00:00:00.000Z"},"containers":{"cna":{"title":"Bypass of Kubernetes API Server proxy TOCTOU","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."}],"affected":[{"vendor":"Kubernetes","product":"Kubernetes","versions":[{"version":"0","status":"affected","lessThan":"*","versionType":"semver"}]}],"references":[{"url":"https://kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/","tags":["x_refsource_MISC"]},{"url":"https://github.com/kubernetes/kubernetes/issues/101493","tags":["x_refsource_MISC"]},{"url":"https://groups.google.com/g/kubernetes-security-announce/c/-MFX60_wdOY","tags":["x_refsource_MISC"]},{"url":"https://security.netapp.com/advisory/ntap-20220225-0002/","tags":["x_refsource_CONFIRM"]}],"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":{"shortName":"kubernetes","orgId":"a6081bf6-c852-4425-ad4f-a67919267565","dateUpdated":"2026-06-01T21:45:40.339Z"},"credits":[{"lang":"en","value":"Javier Provecho"}],"datePublic":"2021-05-04T00:00:00.000Z","source":{"defect":["https://github.com/kubernetes/kubernetes/issues/101493"],"discovery":"EXTERNAL"},"workarounds":[{"lang":"en","value":"If this issue affects your clusters’ 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"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://github.com/kubernetes/kubernetes/issues/101493","tags":["x_refsource_MISC","x_transferred"]},{"url":"https://groups.google.com/g/kubernetes-security-announce/c/-MFX60_wdOY","tags":["x_refsource_MISC","x_transferred"]},{"url":"https://security.netapp.com/advisory/ntap-20220225-0002/","tags":["x_refsource_CONFIRM","x_transferred"]}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2024-08-04T10:03:46.172Z"}}]}}}