Quantum Secular Labs / Blog / Advisories

CVE-2016-9603: Qemu: Buffer overflow

CVE-2016-9603 is rated critical with a CVSS v3.0 base score of 9.9 and affects Qemu, along with 8 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

A heap buffer overflow flaw was found in QEMU's Cirrus CLGD 54xx VGA emulator's VNC display driver support before 2.9; the issue could occur when a VNC client attempted to update its display after a VGA operation is performed by a guest. A privileged user/process inside a guest could use this flaw to crash the QEMU process or, potentially, execute arbitrary code on the host with privileges of the QEMU process.

Severity breakdown

CVSS v3.0 9.9: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: Low. A basic user account is enough.
  • User interaction: None. No action from any user is needed.
  • Scope: Changed. Impact reaches beyond the vulnerable component to other resources.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-122: Heap-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the heap.

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

Affected products

  • Qemu: before 2.9.0
  • Citrix Xenserver: 6.0.2; 6.2.0 sp1; 6.5 sp1; 7.0; 7.1
  • Red Hat Openstack: 5.0; 6.0; 7.0; 8; 9; 10
  • Debian Linux: 7.0
  • Red Hat Enterprise Linux Desktop: 6.0; 7.0
  • Red Hat Enterprise Linux Server: 6.0; 7.0
  • Red Hat Enterprise Linux Server Aus: 7.3; 7.4
  • Red Hat Enterprise Linux Server Eus: 7.3; 7.4; 7.5
  • Red Hat Enterprise Linux Workstation: 6.0; 7.0

References