CVE-2021-3544

Host denial of service via unreleased GPU resources

Published Jun 2, 2021 · Updated Aug 3, 2024

Memory leaks in QEMU vhost-user-gpu 6.0 and earlier allow guest OS users to exhaust host memory through crafted GPU commands. Resource creation, backing attachment, and unref paths in vhost-user-gpu.c and virgl.c omit buffer or iovec release after errors and repeated operations. Access to the vhost-user GPU device is required, and repeated commands can exhaust host memory or crash the host QEMU process.

CVSS severity6.5
Medium
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leaks in QEMU vhost-user-gpu 6.0 and earlier allow guest OS users to exhaust host memory through crafted GPU commands. Resource creation, backing attachment, and unref paths in vhost-user-gpu.c and virgl.c omit buffer or iovec release after errors and repeated operations. Access to the vhost-user GPU device is required, and repeated commands can exhaust host memory or crash the host QEMU process.

The record

CVE
CVE-2021-3544
Published
Jun 2, 2021
Updated
Aug 3, 2024
Vendor
QEMU Project
Product
QEMU
Classifications
CWE-401, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=All QEMU versions up to and including 6.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

QEMU Project · QEMUversion=All QEMU versions up to and including 6.0

Published CVSS scores

3.2Red HatCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:L
6.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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