CVE-2019-18425 Detail
Current Description
An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. There is missing descriptor table limit checking in x86 PV emulation. When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don't install any LDT by default). 32-bit PV guest user mode can elevate its privileges to that of the guest kernel. Xen versions from at least 3.2 onwards are affected. Only 32-bit PV guest user mode can leverage this vulnerability. HVM, PVH, as well as 64-bit PV guests cannot leverage this vulnerability. Arm systems are unaffected.
Source:
MITRE
View Analysis Description
Analysis Description
An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. There is missing descriptor table limit checking in x86 PV emulation. When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don't install any LDT by default). 32-bit PV guest user mode can elevate its privileges to that of the guest kernel. Xen versions from at least 3.2 onwards are affected. Only 32-bit PV guest user mode can leverage this vulnerability. HVM, PVH, as well as 64-bit PV guests cannot leverage this vulnerability. Arm systems are unaffected.
Source:
MITRE
Severity
CVSS 3.x Severity and Metrics:
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0 Severity and Metrics:
Vector: (AV:N/AC:M/Au:N/C:C/I:C/A:C)
References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID |
CWE Name |
Source |
| CWE-269 |
Improper Privilege Management |
NIST
|
Change History
2 change records found
- show changes
Initial Analysis -
11/6/2019 1:38:02 PM
| Action |
Type |
Old Value |
New Value |
| Added |
CPE Configuration |
|
OR
*cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:* versions up to (including) 4.12.1 |
| Added |
CVSS V2 |
|
NIST (AV:N/AC:M/Au:N/C:C/I:C/A:C) |
| Added |
CVSS V3.1 |
|
NIST AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Added |
CWE |
|
NIST CWE-269 |
| Changed |
Reference Type |
http://www.openwall.com/lists/oss-security/2019/10/31/2 No Types Assigned |
http://www.openwall.com/lists/oss-security/2019/10/31/2 Mailing List, Third Party Advisory |
| Changed |
Reference Type |
http://xenbits.xen.org/xsa/advisory-298.html No Types Assigned |
http://xenbits.xen.org/xsa/advisory-298.html Patch, Vendor Advisory |
CVE Modified by MITRE -
10/31/2019 11:15:11 AM
| Action |
Type |
Old Value |
New Value |
| Added |
Reference |
|
http://www.openwall.com/lists/oss-security/2019/10/31/2 [No Types Assigned] |
Quick Info
CVE Dictionary Entry:
CVE-2019-18425
NVD Published Date:
10/31/2019
NVD Last Modified:
11/06/2019
|