CVE-2020-14364
Description
An out-of-bounds read/write access flaw was found in the USB emulator of the QEMU. This issue occurs while processing USB packets from a guest when USBDevice 'setup_len' exceeds its 'data_buf[4096]' in the do_token_in, do_token_out routines. This flaw allows a guest user to crash the QEMU process, resulting in a denial of service, or the potential execution of arbitrary code with the privileges of the QEMU process on the host.
Statement
This issue affects the version of the qemu-kvm package as shipped with the Red Hat Enterprise Linux 6, 7 and 8. Future qemu-kvm package updates for Red Hat Enterprise Linux 6, 7 and 8 may address this issue.
Red Hat Enterprise Linux 5 is now in Maintenance Support 2 Phase of the support and maintenance life cycle. This issue is not currently planned to be addressed in its future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Red Hat OpenStack Platform 15 and newer consume fixes directly from the Red Hat Enterprise Linux 8 Advanced Virtualization repository.
Mitigation
Using Libvirt management interface to manage guest VMs significantly reduces impact of this issue. Libvirt starts each guest process with an unprivileged system user(ex. qemu) privileges and further confines the process with strict sVirt and SELinux policies.
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 | 5 | 5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | High | High | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Changed | N/A |
| Confidentiality | Low | Low | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | Low | Low | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:L
NVD: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:L
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Acknowledgements
Red Hat would like to thank Xiao Wei (360.com) and Ziming Zhang for reporting this issue.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
