SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2021-3750

This can ultimately lead to a use-after-free issue.

HIGH 8.2EPSS 0.51%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.51%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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. This flaw affects QEMU versions before 7.0.0.

CVSS 3.1
8.2 HIGHCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
EPSS
0.51% probability · 43th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-416
Affected
qemu/qemu · redhat/enterprise linux
Source
secalert@redhat.com
EPSS trend
0%3%5%26 October 2026: 0.51%26 October 202626 October 2026

EPSS 0.5% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.