What is CVE-2019-19338?

CVE-2019-19338 is a medium-severity vulnerability in Linux Kernel, classified under Observable Discrepancy. CVSS score: 5.5/10. Published 2020-07-13.

How severe is CVE-2019-19338?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Is CVE-2019-19338 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Linux Kernel

CVE-2019-19338

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.

Published 2020-07-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.005 (39.0th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: +0.000

Affected products

Linux Kernel
[Unknown] Linux Kernel — versions before 5.5
Red Hat Enterprise Linux — versions 6.0

Weakness classification (CWE)

Public proof-of-concept exploits

References

www.openwall.com/lists/oss-security/2019/12/10/3 (Patch, Mailing List, Third Party Advisory)
bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
software.intel.com/security-software-guidance/insights/deep-dive-intel-transact… (Third Party Advisory)

Frequently asked questions

What is CVE-2019-19338?: CVE-2019-19338 is a medium-severity vulnerability in Linux Kernel, classified under Observable Discrepancy. CVSS score: 5.5/10. Published 2020-07-13.
How severe is CVE-2019-19338?: Medium severity. CVSS v3 base score is 5.5 out of 10.
Is CVE-2019-19338 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.