CVE-2019-19338

Kernel: KVM: export MSR_IA32_TSX_CTRL to guest - incomplete fix for TAA (CVE-2019-11135)

Published Jul 13, 2020 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2019-8959 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.
History

No history.

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Aug 5, 2024, 2:16 AM
Reserved
Nov 27, 2019, 12:00 AM
Status
Modified
Published
Jul 13, 2020, 5:15 PM
Modified
Jun 17, 2026, 2:26 AM
Severity
Moderate
Public date
Nov 18, 2019, 12:00 AM