CVE-2020-27671
Description
A flaw was found to occur in the Xen optimization to coalesce per-page IOMMU TLB flushes. This flaw allows malicious x86 HVM and PVH guests to cause host data corruption and data leaks, resulting in a denial of service (DoS) or potential privilege escalation. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.
Statement
All Xen versions from 4.2 onwards are vulnerable. Red Hat Enterprise Linux 5 is not affected by this flaw, as it shipped with an older version of Xen.
Mitigation
Avoid passing through physical devices to untrusted guests. Refer to the XSA-346 advisory for additional information.
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 | 7.8 | 7.8 | 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 | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality
Technical Impact: Modify Application Data; Read Application Data
If a released resource is subsequently reused or reallocated, then an attempt to use the original resource might allow access to sensitive data that is associated with a different user or entity.
Other,Availability
Technical Impact: Other; DoS: Crash, Exit, or Restart
When a resource is released it might not be in an expected state, later attempts to access the resource may lead to resultant errors that may lead to a crash.
Acknowledgements
Red Hat would like to thank the Xen project for reporting this issue.
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