VCPUOP_initialise DoS

2019-10-3112:00:00

Xen Project

xenbits.xen.org

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

6.3 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

SINGLE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

COMPLETE

AV:N/AC:M/Au:S/C:N/I:N/A:C

0.008 Low

EPSS

Percentile

81.8%

JSON

ISSUE DESCRIPTION

hypercall_create_continuation() is a variadic function which uses a printf-like format string to interpret its parameters. Error handling for a bad format character was done using BUG(), which crashes Xen.
One path, via the VCPUOP_initialise hypercall, has a bad format character. The BUG() can be hit if VCPUOP_initialise executes for a sufficiently long period of time for a continuation to be created.

IMPACT

Malicious guests may cause a hypervisor crash, resulting in a Denial of Service (Dos).

VULNERABLE SYSTEMS

Xen versions 4.6 and newer are vulnerable. Xen versions 4.5 and earlier are not vulnerable.
Only x86 PV guests can exploit the vulnerability. HVM and PVH guests, and guests on ARM systems, cannot exploit the vulnerability.