CVE Vulnerabilities

CVE-2016-9962

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Published: Jan 31, 2017 | Modified: Apr 20, 2025
CVSS 3.x
6.4
MEDIUM
Source:
NVD
CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
4.4 MEDIUM
AV:L/AC:M/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
7.5 IMPORTANT
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Ubuntu
MEDIUM

RunC allowed additional container processes via runc exec to be ptraced by the pid 1 of the container. This allows the main processes of the container, if running as root, to gain access to file-descriptors of these new processes during the initialization and can lead to container escapes or modification of runC state before the process is fully placed inside the container.

Weakness

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Affected Software

Name Vendor Start Version End Version
Docker Docker 1.11.0 (including) 1.12.6 (excluding)
Red Hat Enterprise Linux 7 Extras RedHat docker-2:1.12.5-14.el7 *
Red Hat Enterprise Linux 7 Extras RedHat docker-latest-0:1.12.5-14.el7 *
Red Hat Enterprise Linux 7 Extras RedHat runc-0:1.0.0-1.rc2.el7 *
Docker.io Ubuntu artful *
Docker.io Ubuntu bionic *
Docker.io Ubuntu cosmic *
Docker.io Ubuntu devel *
Docker.io Ubuntu disco *
Docker.io Ubuntu esm-apps/bionic *
Docker.io Ubuntu esm-infra/xenial *
Docker.io Ubuntu trusty *
Docker.io Ubuntu upstream *
Docker.io Ubuntu xenial *
Docker.io Ubuntu yakkety *
Docker.io Ubuntu zesty *
Runc Ubuntu artful *
Runc Ubuntu bionic *
Runc Ubuntu cosmic *
Runc Ubuntu devel *
Runc Ubuntu disco *
Runc Ubuntu esm-apps/bionic *
Runc Ubuntu upstream *
Runc Ubuntu yakkety *
Runc Ubuntu zesty *

Extended Description

A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:

A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.

Potential Mitigations

  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.
  • Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

References