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Fencer Intel
low 2.2

CVE-2020-8562 json

Bypass of Kubernetes API Server proxy TOCTOU

published 4y ago modified last mo. also GHSA-qh36-44jv-c8xj , GO-2022-0617 , EUVD-2022-1153

cvss
2.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known

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.

Patch / fix

  • kubernetes Debian 14, Debian 13, Debian 12 1.20.5+really1.20.2-1

debian advisories DEBIAN-CVE-2020-8562

  • govulncheck-vulndb openSUSE Tumbleweed 0.0.20250807T150727-1.1

opensuse advisories openSUSE-SU-2025:15424-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-8562 updated cvss 2.2

kubernetes: Bypass of Kubernetes API Server proxy TOCTOU

  • Red Hat OpenShift Container Platform 3.11 atomic-openshift, atomic-openshift-pod, atomic-openshift-node, atomic-openshift-tests, atomic-openshift-master, atomic-openshift-clients, +7 more Red Hat OpenShift Container Platform 4 openshift, openshift-clients, openshift-kubelet, openshift-hyperkube, openshift-kube-apiserver, openshift-kube-scheduler, +2 more
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.19% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 2.2 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N
NVD 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:P/I:N/A:N
GitHub 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
go k8s.io/kubernetes
>=1.21.0, <=1.21.1
>=1.20.0, <=1.20.7
>=1.19.0, <=1.19.11
<=1.18.19
 no fix listed

Affected products

  • Kubernetes Kubernetes

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.