Vulnerability in Kubernetes
CVE-2020-8562
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.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
EPSS: 0.011 (61.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 2.2 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Kubernetes — versions unspecified, 1.21.0, next of v1.18.18
Weakness classification (CWE)
Public proof-of-concept exploits
References
- jordan@liggitt.net (Third Party Advisory, x_refsource_MISC, Mitigation, Issue Tracking)
- jordan@liggitt.net (Mailing List, Third Party Advisory, x_refsource_MISC)
- jordan@liggitt.net (x_refsource_CONFIRM, Third Party Advisory)
- jordan@liggitt.net (x_refsource_MISC)
Frequently asked questions
- What is CVE-2020-8562?
- CVE-2020-8562 is a low-severity vulnerability in Kubernetes, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 2.2/10. Published 2022-02-01.
- How severe is CVE-2020-8562?
- Low severity. CVSS v3 base score is 2.2 out of 10.
- Is CVE-2020-8562 known to be exploited?
- 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.