An issue was discovered in Xen through 4.12.x allowing 32-bit Arm guest OS users to cause a denial of service (out-of-bounds access) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On 32-bit Arm accesses to bitmaps with bit a count which is a multiple of 32, an out of bounds access may occur. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. 32-bit Arm systems are vulnerable. 64-bit Arm systems are not vulnerable.

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Source: MITRE

Published: 2019-12-11

Updated: 2020-01-03

Type: CWE-119

Risk Information

CVSS v2.0

Base Score: 2.1

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

Impact Score: 2.9

Exploitability Score: 3.9

Severity: LOW

CVSS v3.0

Base Score: 6.5

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

Impact Score: 4

Exploitability Score: 2

Severity: MEDIUM