Xen Bad error path in GNTTABOP_map_grant DoS (XSA-316)

medium Nessus Plugin ID 135928

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Synopsis

The remote Xen hypervisor installation is missing a security update.

Description

According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a denial of service vulnerability. Grant table operations are expected to return 0 for success, and a negative number for errors. Some misplaced brackets cause one error path to return 1 instead of a negative value. The grant table code in Linux treats this condition as success, and proceeds with incorrectly initialised state. A buggy or malicious guest can construct its grant table in such a way that, when a backend domain tries to map a grant, it hits the incorrect error path. This will crash a Linux based dom0 or backend domain.

Note only systems with the XSA-295 patch applied are affected. All other hosts are not vulnerable.

Solution

Apply the appropriate patch or workaround according to the vendor advisory.

Plugin Details

Severity: Medium

ID: 135928

File Name: xen_server_XSA-316.nasl

Version: 1.6

Type: local

Family: Misc.

Published: 4/24/2020

Updated: 3/14/2024

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Low

Base Score: 2.1

Temporal Score: 1.6

Vector: CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2020-11743

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 5

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

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:xen:xen

Required KB Items: Settings/ParanoidReport, installed_sw/Xen Hypervisor

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/14/2020

Vulnerability Publication Date: 4/14/2020

Reference Information

CVE: CVE-2020-11743

IAVB: 2020-B-0019-S

Detections

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