CVE-2021-3750
QEMU: hcd-ehci: DMA reentrancy issue leads to use-after-free
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · August 26, 2020
Updated · June 28, 2026
Description
A DMA reentrancy issue was found in the USB EHCI controller emulation of QEMU. EHCI does not verify if the Buffer Pointer overlaps with its MMIO region when it transfers the USB packets. Crafted content may be written to the controller's registers and trigger undesirable actions (such as reset) while the device is still transferring packets. This can ultimately lead to a use-after-free issue. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition, or potentially execute arbitrary code within the context of the QEMU process on the host.
Statement
This CVE is rated as having a Moderate security impact on Red Hat Enterprise Linux. For additional details, refer to https://bugzilla.redhat.com/show_bug.cgi?id=1999073#c5.
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 · 7.5CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
CWE-416 · Use After Free