National Vulnerability Database

National Vulnerability Database

National Vulnerability
Database

CVE-2018-12892 Detail

Current Description

An issue was discovered in Xen 4.7 through 4.10.x. libxl fails to pass the readonly flag to qemu when setting up a SCSI disk, due to what was probably an erroneous merge conflict resolution. Malicious guest administrators or (in some situations) users may be able to write to supposedly read-only disk images. Only emulated SCSI disks (specified as "sd" in the libxl disk configuration, or an equivalent) are affected. IDE disks ("hd") are not affected (because attempts to make them readonly are rejected). Additionally, CDROM devices (that is, devices specified to be presented to the guest as CDROMs, regardless of the nature of the backing storage on the host) are not affected; they are always read only. Only systems using qemu-xen (rather than qemu-xen-traditional) as the device model version are vulnerable. Only systems using libxl or libxl-based toolstacks are vulnerable. (This includes xl, and libvirt with the libxl driver.) The vulnerability is present in Xen versions 4.7 and later. (In earlier versions, provided that the patch for XSA-142 has been applied, attempts to create read only disks are rejected.) If the host and guest together usually support PVHVM, the issue is exploitable only if the malicious guest administrator has control of the guest kernel or guest kernel command line.

Source:  MITRE
Description Last Modified:  07/02/2018
View Analysis Description

Impact

CVSS v3.0 Severity and Metrics:

Base Score: 9.9 CRITICAL
Vector: AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H (V3 legend)
Impact Score: 6.0
Exploitability Score: 3.1


Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Changed
Confidentiality (C): High
Integrity (I): High
Availability (A): High

CVSS v2.0 Severity and Metrics:

Base Score: 6.5 MEDIUM
Vector: (AV:N/AC:L/Au:S/C:P/I:P/A:P) (V2 legend)
Impact Subscore: 6.4
Exploitability Subscore: 8.0


Access Vector (AV): Network
Access Complexity (AC): Insufficient_Info
Authentication (AU): Single
Confidentiality (C): Partial
Integrity (I): Partial
Availability (A): Partial
Additional Information:
Allows unauthorized disclosure of information
Allows unauthorized modification
Allows disruption of service

References to Advisories, Solutions, and Tools

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Hyperlink Resource
http://www.openwall.com/lists/oss-security/2018/06/27/12 Mailing List Third Party Advisory
http://www.securityfocus.com/bid/104571 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1041203 Third Party Advisory VDB Entry
http://xenbits.xen.org/xsa/advisory-266.html Vendor Advisory
https://security.gentoo.org/glsa/201810-06 Third Party Advisory
https://www.debian.org/security/2018/dsa-4236 Third Party Advisory

Technical Details

Vulnerability Type (View All)

  • Information Leak / Disclosure (CWE-200)

Known Affected Software Configurations Switch to CPE 2.2

Configuration 1 ( hide )
 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
     Show Matching CPE(s)

Configuration 2 ( hide )
 cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*
     Show Matching CPE(s)
From (including)
4.7.0
Up to (including)
4.10.1


Change History

4 change records found - show changes

Quick Info

CVE Dictionary Entry:
CVE-2018-12892
NVD Published Date:
07/02/2018
NVD Last Modified:
03/29/2019