CVE-2015-2756: Canonical Ubuntu Linux

Medium severity, CVSS 4.9. EPSS: 0.5% chance of exploitation in the next 30 days.

QEMU, as used in Xen 3.3.x through 4.5.x, does not properly restrict access to PCI command registers, which might allow local HVM guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response.

Affected products

• Canonical Ubuntu Linux: version 12.04 only; version 14.04 only; version 14.10 only; version 15.04 only
• Debian Debian Linux: version 7.0 only; version 8.0 only
• Fedoraproject Fedora: version 20 only; version 21 only
• Xen Xen: version 4.3.0 only; version 4.3.1 only; version 4.3.2 only; version 4.4.0 only; version 4.4.1 only; version 4.5.0 only

Published 2015-04-01. Last modified 2026-06-17.