CVE-2019-5736
Description
A flaw was found in the way runc handled system file descriptors when running containers. A malicious container could use this flaw to overwrite contents of the runc binary and consequently run arbitrary commands on the container host system.
Security Bulletin
Statement
The 'docker' package shipped in Red Hat Enterprise Linux 7 Extras bundles 'runc' since 'docker' starting from version 1.12. Both the 'docker' and 'runc' packages are affected by this issue.
The 'docker-latest' package is deprecated as of Red Hat Enterprise Linux 7.5. Customers using this package should update to the latest 'docker' package shipped in Red Hat Enterprise Linux 7 Extras.
OpenShift Container Platform (OCP) versions 3.9 and later use 'docker' version 1.13 in the default configuration but can be configured to use CRI-O as an alternative, which depends on the 'runc' package. OCP versions 3.9 and later should use the updated 'docker' and 'runc' packages shipped in Red Hat Enterprise Linux 7 Extras.
OCP versions 3.4 through 3.7 originally used 'docker' version 1.12 from the Red Hat Enterprise Linux 7 Extras channel. An updated version of 'docker' 1.12 has been delivered to the RPM channels for OCP versions 3.4 through 3.7.
OCP version 3.9 previously shipped a version of 'runc' in it's RPM repository. OCP 3.9 clusters using CRI-O should update 'runc' from the Red Hat Enterprise Linux 7 Extras channel.
Red Hat Enterprise Linux Atomic Host 7 is not affected by this vulnerability as the target runc binaries are stored on a read-only filesystem and cannot be overwritten.
Mitigation
This vulnerability is mitigated on Red Hat Enterprise Linux 7 if SELinux is in enforcing mode. SELinux in enforcing mode is a pre-requisite for OpenShift Container Platform 3.x.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert: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 Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.7 | 8.6 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | Required | Required | N/A |
| Scope | Changed | Changed | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality
Technical Impact: Modify Application Data; Read Application Data
If a released resource is subsequently reused or reallocated, then an attempt to use the original resource might allow access to sensitive data that is associated with a different user or entity.
Other,Availability
Technical Impact: Other; DoS: Crash, Exit, or Restart
When a resource is released it might not be in an expected state, later attempts to access the resource may lead to resultant errors that may lead to a crash.
Acknowledgements
Red Hat would like to thank the Open Containers Security Team for reporting this issue. Upstream acknowledges Adam Iwaniuk and Borys Popławski as the original reporters.
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