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

Quick assessment

Affected
Kubernetes Kubernetes
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Kubernetes是美国Linux基金会的一套开源的Docker容器集群管理系统。该系统为容器化的应用提供资源调度、部署运行、服务发现和扩容缩容等功能。 Kubernetes 存在安全漏洞，该漏洞源于授权用户可能能够访问Kubernetes控制平面组件上的专用网络。只有当不受信任的用户可以创建或修改Node对象及其代理，或者不受信任的用户可以创建或修改StorageClass对象并访问KubeControllerManager日志时，Kubernetes集群才会受到影响。

CVSS 2.2 · Low EPSS 1.08% · P64

Possible ATT&CK Techniques 1 AI

T1071.004 · DNS

Affected Version Matrix 1

VendorProduct Version RangeStatus
Kubernetes Kubernetes < * affected
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I. Basic Information for CVE-2020-8562

Vulnerability Information
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Vulnerability Title
Bypass of Kubernetes API Server proxy TOCTOU
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5
Vulnerability Title
Kubernetes 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Kubernetes是美国Linux基金会的一套开源的Docker容器集群管理系统。该系统为容器化的应用提供资源调度、部署运行、服务发现和扩容缩容等功能。 Kubernetes 存在安全漏洞，该漏洞源于授权用户可能能够访问Kubernetes控制平面组件上的专用网络。只有当不受信任的用户可以创建或修改Node对象及其代理，或者不受信任的用户可以创建或修改StorageClass对象并访问KubeControllerManager日志时，Kubernetes集群才会受到影响。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Kubernetes Kubernetes 0 ~ * -

II. Public POCs for CVE-2020-8562

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III. Intelligence Information for CVE-2020-8562

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Vendor Advisories for CVE-2020-8562 (1)

Security Blog Posts for CVE-2020-8562 (1)

Other References for CVE-2020-8562 (2)

IV. Related Vulnerabilities

Same product: Kubernetes
Same vendor: Kubernetes
Same weakness: CWE-367

V. Comments for CVE-2020-8562

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