CVE-2019-11135
Description
A flaw was found in the way Intel CPUs handle speculative execution of instructions when the TSX Asynchronous Abort (TAA) error occurs. A local authenticated attacker with the ability to monitor execution times could infer the TSX memory state by comparing abort execution times. This could allow information disclosure via this observed side-channel for any TSX transaction being executed while an attacker is able to observe abort timing.
Intel's Transactional Synchronisation Extensions (TSX) are set of instructions which enable transactional memory support to improve performance of the multi-threaded applications, in the lock-protected critical sections. The CPU executes instructions in the critical-sections as transactions, while ensuring their atomic state. When such transaction execution is unsuccessful, the processor cannot ensure atomic updates to the transaction memory, so the processor rolls back or aborts such transaction execution.
While TSX Asynchronous Abort (TAA) is pending, CPU may continue to read data from architectural buffers and pass it to the dependent speculative operations. This may cause information leakage via speculative side-channel means, which is quite similar to the Microarchitectural Data Sampling (MDS) issue.
Statement
libvirt and qemu-kvm on Red Hat Enterprise Linux 6 are not affected by this vulnerability as they do not support MSR-based CPU features.
Mitigation
For mitigation related information, please refer to the Red Hat Knowledgebase article: https://access.redhat.com/solutions/tsx-asynchronousabort
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | 6.5 | 6.5 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Changed | Changed | Changed |
| Confidentiality | High | High | High |
| Integrity Impact | None | None | None |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality,Other
Technical Impact: Read Application Data; Other
Information exposure.
Acknowledgements
Red Hat would like to thank Intel for reporting this issue.
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