CVE-2020-14386

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Last Modified: UTC

Important Important Impact What does this mean?
7.8 CVSS v3 Base Score

Description

A flaw was found in the Linux kernel. Memory corruption can be exploited to gain root privileges from unprivileged processes. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Statement

Only local users with CAP_NET_RAW capability enabled can trigger this issue.

For OpenShift Container Platform 4, pods in the default restricted SCC are granted CAP_NET_RAW by default. An attacker can exploit this if they can run arbitrary container images on the target cluster.

Mitigation

If the CAP_NET_RAW capability disabled by default (which is true for Red Hat Enterprise Linux), then only a privileged user can trigger this bug. The mitigation is to disable CAP_NET_RAW capability for regular users and for executables.

On Red Hat Enterprise Linux 8 CAP_NET_RAW capability can be also gained by exploiting unprivileged user namespaces. The mitigation is to disable unprivileged user namespaces by setting user.max_user_namespaces to 0:

# echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf
# sysctl -p /etc/sysctl.d/userns.conf

OpenShift Container Platform 4.5 and 4.4 this can be mitigated by removing `CAP_NET_RAW` from the default cri-o capabilities provided to pods (NOTE: This may prevent `ping` from working in unprivileged pods. This fix has not been validated for OpenShift 4.3 or below):

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker
  name: 50-reset-crio-capabilities
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:text/plain;charset=utf-8;base64,W2NyaW8ucnVudGltZV0KZGVmYXVsdF9jYXBhYmlsaXRpZXMgPSBbCiAgICAiQ0hPV04iLAogICAgIkRBQ19PVkVSUklERSIsCiAgICAiRlNFVElEIiwKICAgICJGT1dORVIiLAogICAgIlNFVEdJRCIsCiAgICAiU0VUVUlEIiwKICAgICJTRVRQQ0FQIiwKICAgICJORVRfQklORF9TRVJWSUNFIiwKICAgICJTWVNfQ0hST09UIiwKICAgICJLSUxMIiwKXQo=
        filesystem: root
        mode: 0644
        path: /etc/crio/crio.conf.d/reset-crio-capabilities.conf

Create this MachineConfig object via e.g. `oc apply`. More information about MachineConfig can be found here:
This content is not included.https://github.com/openshift/machine-config-operator
https://docs.openshift.com/container-platform/4.5/architecture/architecture-rhcos.html

In order to monitor the rollout of this change, use `oc describe machineconfigpool/worker`.

Check for any pods which start to crash after this is applied; they may need to be adjusted request `CAP_NET_RAW` explicitly. More information:
This content is not included.https://kubernetes.io/docs/tasks/configure-pod-container/security-context/#set-capabilities-for-a-container
This page is not included, but the link has been rewritten to point to the nearest parent document.https://docs.openshift.com/container-platform/4.5/authentication/managing-security-context-constraints.html

Additional Information

External References

Content from www.cve.org is not included.https://www.cve.org/CVERecord?id=CVE-2020-14386

Content from nvd.nist.gov is not included.https://nvd.nist.gov/vuln/detail/CVE-2020-14386

Content from git.kernel.org is not included.https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=acf69c946233259ab4d64f8869d4037a198c7f06

Content from seclists.org is not included.https://seclists.org/oss-sec/2020/q3/146

Affected Packages and Issued Red Hat Security Errata

Products / Services Components State Errata
Red Hat Enterprise Linux 5 kernel Not affected
Red Hat Enterprise Linux 6 kernel Not affected
Red Hat Enterprise Linux 7 kernel Not affected
Red Hat Enterprise Linux 7 kernel-alt Not affected
Red Hat Enterprise Linux 7 kernel-rt Not affected
Red Hat Enterprise Linux 8 kernel Fixed RHSA-2020:4286
Red Hat Enterprise Linux 8 kernel-rt Fixed RHSA-2020:4289
Red Hat Enterprise Linux 8 kpatch-patch Fixed RHSA-2020:4331
Red Hat Enterprise Linux 8.0 Update Services for SAP Solutions kernel Fixed RHSA-2020:5199
Red Hat Enterprise Linux 8.1 Extended Update Support kernel Fixed RHSA-2020:4287
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authorities (CNA) source for its products and services (see Red Hat classifications ).

CVSS v3 Score Breakdown Red Hat NVD
CVSS v3 Base Score 7.8 7.8
Attack Vector Local Local
Attack Complexity Low Low
Privileges Required Low Low
User Interaction None None
Scope Unchanged Unchanged
Confidentiality Impact High High
Integrity Impact High High
Availability Impact High High

CVSS v3 Vector

Red Hat CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Red Hat CVSS v3 Score Explanation

While PR:H is technically correct because of the CAP_NET_RAW capability requirement, unprivileged users on the system with unprivileged user namespaces enabled (this seems to be default among distributions) can grant themselves CAP_NET_RAW capability easily, so in practice, it's PR:L.

Acknowledgements

Red Hat would like to thank Or Cohen (paloaltonetworks.com) for reporting this issue.

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

 For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.

What can I do if my product is listed as "Will not fix"?

 A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

 A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

 A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

 The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

 In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our This content is not included.Red Hat Vulnerability Scanner Certification program.