CVE-2019-18425

critical
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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.

References

http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00037.html

http://www.openwall.com/lists/oss-security/2019/10/31/2

http://xenbits.xen.org/xsa/advisory-298.html

https://lists.fedoraproject.org/archives/list/[email protected]/message/2BQKX7M2RHCWDBKNPX4KEBI3MJIH6AYZ/

https://lists.fedoraproject.org/archives/list/[email protected]/message/I5WWPW4BSZDDW7VHU427XTVXV7ROOFFW/

Details

Source: MITRE

Published: 2019-10-31

Updated: 2019-11-14

Type: CWE-269

Risk Information

CVSS v2

Base Score: 9.3

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

Impact Score: 10

Exploitability Score: 8.6

Severity: HIGH

CVSS v3

Base Score: 9.8

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

Impact Score: 5.9

Exploitability Score: 3.9

Severity: CRITICAL

Vulnerable Software

Configuration 1

OR

cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:* versions up to 4.12.1 (inclusive)

Tenable Plugins

View all (15 total)

IDNameProductFamilySeverity
150584SUSE SLES11 Security Update : xen (SUSE-SU-2020:14444-1)NessusSuSE Local Security Checks
critical
134964GLSA-202003-56 : Xen: Multiple vulnerabilities (MDSUM/RIDL) (MFBDS/RIDL/ZombieLoad) (MLPDS/RIDL) (MSBDS/Fallout)NessusGentoo Local Security Checks
critical
133763SUSE SLES12 Security Update : xen (SUSE-SU-2020:0388-1)NessusSuSE Local Security Checks
critical
133539SUSE SLES12 Security Update : xen (SUSE-SU-2020:0334-1)NessusSuSE Local Security Checks
critical
132875Debian DSA-4602-1 : xen - security update (MDSUM/RIDL) (MFBDS/RIDL/ZombieLoad) (MLPDS/RIDL) (MSBDS/Fallout)NessusDebian Local Security Checks
critical
132073SUSE SLES12 Security Update : xen (SUSE-SU-2019:3297-1)NessusSuSE Local Security Checks
critical
131460Fedora 30 : xen (2019-cbb732f760)NessusFedora Local Security Checks
critical
131143Fedora 31 : xen (2019-376ec5c107)NessusFedora Local Security Checks
critical
131098Fedora 29 : xen (2019-865bb16900)NessusFedora Local Security Checks
critical
131062openSUSE Security Update : xen (openSUSE-2019-2508)NessusSuSE Local Security Checks
critical
131060openSUSE Security Update : xen (openSUSE-2019-2506)NessusSuSE Local Security Checks
critical
130960SUSE SLED12 / SLES12 Security Update : xen (SUSE-SU-2019:2962-1)NessusSuSE Local Security Checks
critical
130959SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2019:2961-1)NessusSuSE Local Security Checks
critical
130958SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2019:2960-1)NessusSuSE Local Security Checks
critical
130760Xen Project Descriptor Table Limit Checking Privilege Escalation Vulnerability (XSA-298)NessusMisc.
critical