CVE-2020-0550
Description
A flaw was found in the Intel CPU's cache coherency mechanism. A microarchitectural (hardware) implementation issue that could allow an unprivileged local attacker to bypass conventional system security controls to infer on-CPU Level 1 cache contents is present. At this time, this specific flaw is only known to affect Intel-based processors. The highest threat from this vulnerability is to data confidentiality.
Statement
CVE-2020-0550 is the CVE assigned specifically to the hardware implementation leading to this flaw. Unlike the L1TF microarchitectural issue, no additional CVE have been assigned at this time to cover operating systems or vmm/hypervisor specific implementations.
As this CVE is a flaw in specific hardware, not the operating system kernel, and operating system mitigations are already applied, Red Hat does not list the Red Hat Enterprise Linux kernel package as “affected” by this CVE.
This does not imply that the flaw can not be exposed on systems running Red Hat Enterprise Linux on vulnerable hardware, only that the flaw exists in the hardware implementation and no additional changes are deemed necessary or practical to address this flaw at the software layer.
Existing mitigations released in Red Hat Enterprise Linux in response to Spectre V1 (https://access.redhat.com/security/vulnerabilities/speculativeexecution), L1TF (https://access.redhat.com/security/vulnerabilities/L1TF) and MDS (https://access.redhat.com/security/vulnerabilities/mds) should already provide significant barrier against exploitation of this attack vector and no new mitigation is planned at this time.
Mitigation
Due to the high level of difficulty of the attack and the performance impact which would be associated with any potential mitigations, there are currently no microcode or software mitigations for this issue, other than the existing L1TF mitigations described above, which protect virtual machines against other virtual machines on the host; and disabling TSX, as described above, which can raise the bar of difficulty of the attack.
Red Hat doesn't currently have knowledge of any real-world occurrences of this attack, so the risk of attack may be considered low. To further minimize the possibility of attacks related to this and other speculative issues, trusted and untrusted workloads can be isolated on separate systems.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.6 | 5.6 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Changed | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
NVD: CVSS:3.1/AV:L/AC:H/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.
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