Unrestricted qemu logging

2016-05-2317:09:00

Xen Project

xenbits.xen.org

2.1 Low

CVSS2

Attack Vector

LOCAL

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

PARTIAL

AV:L/AC:L/Au:N/C:N/I:N/A:P

6.5 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

0.001 Low

EPSS

Percentile

26.7%

JSON

ISSUE DESCRIPTION

When the libxl toolstack launches qemu for HVM guests, it pipes the output of stderr to a file in /var/log/xen. This output is not rate-limited in any way. The guest can easily cause qemu to print messages to stderr, causing this file to become arbitrarily large.

IMPACT

The disk containing the logfile can be exausted, possibly causing a denial-of-service (DoS).

VULNERABLE SYSTEMS

All versions of Xen are affected.
Only x86 systems are affected; ARM systems are not affected.
Only systems running HVM guests are affected; systems running only PV guests are not affected.
Both qemu-upstream and qemu-traditional are affected.