CVE-2021-3735
QEMU: ahci: deadlock issue leads to denial of service
Severity
LowRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · August 24, 2021
Updated · June 28, 2026
Description
A deadlock issue was found in the AHCI controller device of QEMU. It occurs on a software reset (ahci_reset_port) while handling a host-to-device Register FIS (Frame Information Structure) packet from the guest. A privileged user inside the guest could use this flaw to hang the QEMU process on the host, resulting in a denial of service condition. The highest threat from this vulnerability is to system availability.
Statement
This issue affects the versions of qemu-kvm as shipped with Red Hat Enterprise Linux 8 and Red Hat Enterprise Linux 8 Advanced Virtualization. A future update may address this flaw.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
CVSS / CWE
CVSS 3.1 · 3.2CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:L
CWE-833 · Deadlock