CVE-2019-19338 Information

Description

A flaw was found in the fix for CVE-2019-11135 in the Linux upstream kernel versions before 5.5 where the way Intel CPUs handle speculative execution of instructions when a TSX Asynchronous Abort (TAA) error occurs. When a guest is running on a host CPU affected by the TAA flaw (TAA_NO=0) but is not affected by the MDS issue (MDS_NO=1) the guest was to clear the affected buffers by using a VERW instruction mechanism. But when the MDS_NO=1 bit was exported to the guests the guests did not use the VERW mechanism to clear the affected buffers. This issue affects guests running on Cascade Lake CPUs and requires that host has ‘TSX’ enabled. Confidentiality of data is the highest threat associated with this vulnerability.

CVSS Vector

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

Reference

https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-19338 https://software.intel.com/security-software-guidance/insights/deep-dive-intel-transactional-synchronization-extensions-intel-tsx-asynchronous-abort https://www.openwall.com/lists/oss-security/2019/12/10/3

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

NONE

Base Score

NONE

Base Severity

5.5