CVE-2021-3713

What it is

An out-of-bounds write flaw was found in the UAS (USB Attached SCSI) device emulation of QEMU in versions prior to 6.2.0-rc0. The device uses the guest supplied stream number unchecked, which can lead to out-of-bounds access to the UASDevice->data3 and UASDevice->status3 fields. A malicious guest user could use this flaw to crash QEMU or potentially achieve code execution with the privileges of the QEMU process on the host.

At a glance

Exploitability

Can be exploited with physical access with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-08-25 19:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:05 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.6% in the next 30 days (EPSS).
• Severity: 7.4 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-08-25 19:15 UTC

Last modified

2026-06-17 04:05 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-787 · Out-of-bounds write

Record status

Modified

Affected

• Qemu ≤ 6.1.0
• Debian Linux 9.0
• Debian Linux 10.0
• Debian Linux 11.0

Attack profile CVSS 3.1 · 7.4

Attack vector

Physical

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-3713.md and follow it. Check whether this project is affected by CVE-2021-3713. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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