CVE Vulnerabilities

CVE-2019-11251

Improper Link Resolution Before File Access ('Link Following')

Published: Feb 03, 2020 | Modified: Feb 06, 2020
CVSS 3.x
5.7
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
CVSS 2.x
4.3 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N
RedHat/V2
RedHat/V3
5.3 MODERATE
CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
Ubuntu
MEDIUM

The Kubernetes kubectl cp command in versions 1.1-1.12, and versions prior to 1.13.11, 1.14.7, and 1.15.4 allows a combination of two symlinks provided by tar output of a malicious container to place a file outside of the destination directory specified in the kubectl cp invocation. This could be used to allow an attacker to place a nefarious file using a symlink, outside of the destination tree.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Name Vendor Start Version End Version
Kubernetes Kubernetes 1.13.0 (including) 1.13.11 (excluding)
Kubernetes Kubernetes 1.14.0 (including) 1.14.7 (excluding)
Kubernetes Kubernetes 1.15.0 (including) 1.15.4 (excluding)
Kubernetes Kubernetes 1.1-1.12 (including) 1.1-1.12 (including)
Red Hat OpenShift Container Platform 3.11 RedHat atomic-openshift-0:3.11.154-1.git.0.7a097ad.el7 *
Red Hat OpenShift Container Platform 3.9 RedHat atomic-openshift-0:3.9.102-1.git.0.6411f52.el7 *
Red Hat OpenShift Container Platform 4.1 RedHat openshift-0:4.1.21-201910220952.git.0.493dbf6.el7 *
Red Hat OpenShift Container Platform 4.1 RedHat openshift4/ose-cli:v4.1.21-201910230924 *
Kubernetes Ubuntu disco *
Kubernetes Ubuntu eoan *
Kubernetes Ubuntu groovy *
Kubernetes Ubuntu hirsute *
Kubernetes Ubuntu impish *
Kubernetes Ubuntu kinetic *
Kubernetes Ubuntu lunar *
Kubernetes Ubuntu mantic *

Potential Mitigations

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

References