What’s Vulnerable › Vulnerabilities

CVE-2019-19338

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-07-13 · updated 2026-06-17
• Weakness: CWE-203

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.

Affected products

• Linux kernel: before 5.5 — fixed in 5.5
• Red Hat Enterprise Linux: 6.0

How to fix

Upgrade to a fixed version: Linux kernel 5.5. Check the vendor advisory for mitigations.

References

• 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
• 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

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