Vulnerability CVE-2020-8562


Published: 2022-02-01

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.

Type:

CWE-367

(Time-of-check Time-of-use (TOCTOU) Race Condition)

CVSS2 => (AV:N/AC:M/Au:S/C:P/I:N/A:N)

CVSS Base Score
Impact Subscore
Exploitability Subscore
3.5/10
2.9/10
6.8/10
Exploit range
Attack complexity
Authentication
Remote
Medium
Single time
Confidentiality impact
Integrity impact
Availability impact
Partial
None
None
Affected software
Kubernetes -> Kubernetes 

 References:
https://groups.google.com/g/kubernetes-security-announce/c/-MFX60_wdOY
https://github.com/kubernetes/kubernetes/issues/101493

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