CVE-2021-0145
Description
A flaw was found in microcode. Fast store forwarding prediction in one domain could be controlled by software previously executed in another domain. Such control helps a malicious program running in user mode (or guest VM) to trigger transient execution gadgets in supervisor mode (or VMM), potentially leading to sensitive data disclosure. Fast store forward prediction is not enabled when SSBD is set. This flaw allows an authenticated user with local access to perform information disclosure via transient execution.
Statement
Red Hat has very limited to no visibility and control over binary blobs provided by third-party vendors. Red Hat relies heavily on the vendors to provide timely updates and information about included changes for this content and in most cases merely acts as a release vehicle between the third-party vendor and Red Hat customers with no possibility of influencing or even documenting the changes. Unless explicitly stated, the level of insight, oversight, and control Red Hat has does not meet the criteria required (in terms of Red Hat owned development processes and QA, documentation) for releasing this content as RHSA. For more information please contact the binary content vendor.
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 | 6.5 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Unchanged | 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: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:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Access Control
Technical Impact: Bypass Protection Mechanism
If security-critical decisions rely on a variable having a "0" or equivalent value, and the programming language performs this initialization on behalf of the programmer, then a bypass of security may occur.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The uninitialized data may contain values that cause program flow to change in ways that the programmer did not intend. For example, if an uninitialized variable is used as an array index in C, then its previous contents may produce an index that is outside the range of the array, possibly causing a crash or an exit in other environments.
Acknowledgements
Red Hat would like to thank Intel for reporting this issue.
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