CVE-2021-3682: Debian Linux

High severity, CVSS 8.5. EPSS: 2.9% chance of exploitation in the next 30 days.

A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2. It occurs when dropping packets during a bulk transfer from a SPICE client due to the packet queue being full. A malicious SPICE client could use this flaw to make QEMU call free() with faked heap chunk metadata, resulting in a crash of QEMU or potential code execution with the privileges of the QEMU process on the host.

Affected products

• Debian Debian Linux: version 9.0 only; version 10.0 only; version 11.0 only
• Qemu Qemu: before 6.1.0 (fixed in 6.1.0); version 6.1.0 only
• Red Hat Enterprise Linux: version 8.0 only

Published 2021-08-05. Last modified 2026-06-17.