CVE-2021-3682 — Release of Invalid Pointer or Reference in Qemu
Severity
8.5HIGHNVD
OSV6.5
EPSS
0.4%
top 38.14%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
Timeline
PublishedAug 5
Latest updateDec 27
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:HExploitability: 1.8 | Impact: 6.0
Affected Packages11 packages
Also affects: Debian Linux 10.0, 11.0, 9.0, Enterprise Linux 8.0
Patches
🔴Vulnerability Details
4📋Vendor Advisories
5Microsoft▶
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↗2021-08-10
Debian▶
CVE-2021-3682: qemu - A flaw was found in the USB redirector device emulation of QEMU in versions prio...↗2021
📄Research Papers
1arXiv▶
Breaking Isolation: A New Perspective on Hypervisor Exploitation via Cross-Domain Attacks↗2025-12-27