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CVE-2020-8562

CVE-2020-8562 · Bypass of Kubernetes API Server proxy TOCTOU

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 2.2 · Low · EPSS 1.1% · Fix available

Published
Updated

Stack: system · containers

Affected products and versions

  • kubernetes

    Versions
    • ≥ 0: Affected (semver)

    No fix published

  • kubernetes Debian:12

    Affected ranges
    • ECOSYSTEM: < 1.20.5+really1.20.2-1

    Update to 1.20.5+really1.20.2-1

  • kubernetes Debian:13

    Affected ranges
    • ECOSYSTEM: < 1.20.5+really1.20.2-1

    Update to 1.20.5+really1.20.2-1

  • kubernetes Debian:14

    Affected ranges
    • ECOSYSTEM: < 1.20.5+really1.20.2-1

    Update to 1.20.5+really1.20.2-1

Original sources

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