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HIGH

CVE-2021-4206

CVSS v3

8.2

HIGH

EPSS Score

0.8 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • hivexAlmaLinux:8all versions · fixed in 1.3.18-23.module_el8.6.0+2880+7d9e3703and 6 other packages
  • libguestfsAlmaLinux:8all versions · fixed in 1:1.44.0-5.module_el8.6.0+2880+7d9e3703.almaand 24 other packages
  • libguestfs-winsupportAlmaLinux:8all versions · fixed in 8.6-1.module_el8.6.0+2880+7d9e3703
  • libiscsiAlmaLinux:8all versions · fixed in 1.18.0-8.module_el8.6.0+2880+7d9e3703and 2 other packages
  • libnbdAlmaLinux:8all versions · fixed in 1.6.0-5.module_el8.6.0+2880+7d9e3703and 6 other packages
  • libtpmsAlmaLinux:8all versions · fixed in 0.9.1-0.20211126git1ff6fe1f43.module_el8.6.0+2880+7d9e3703and 1 other package
  • libvirtAlmaLinux:8all versions · fixed in 8.0.0-5.2.module_el8.6.0+3071+a07c0ea5and 27 other packages
  • libvirt-dbusAlmaLinux:8all versions · fixed in 1.3.0-2.module_el8.6.0+2880+7d9e3703

10 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-4206 Red Hat Product Security1,692 products fixed · 64 known affected

    QEMU: QXL: integer overflow in cursor_alloc() can lead to heap buffer overflow

    qemu-guest-agent as a component of Red Hat Enterprise Linux 6 · qemu-guest-agent-win32 as a component of Red Hat Enterprise Linux 6 · qemu-img as a component of Red Hat Enterprise Linux 6

  • RHSA-2022:5821 Red Hat Product Security938 products fixed

    Red Hat Security Advisory: virt:rhel and virt-devel:rhel security, bug fix, and enhancement update

  • RHSA-2022:5002 Red Hat Product Security754 products fixed

    Red Hat Security Advisory: virt:av and virt-devel:av security and bug fix update

Full record on NVD

Description

A flaw was found in the QXL display device emulation in QEMU. An integer overflow in the cursor_alloc() function can lead to the allocation of a small cursor object followed by a subsequent heap-based buffer overflow. This flaw allows a malicious privileged guest user to crash the QEMU process on the host or potentially execute arbitrary code within the context of the QEMU process.

Technical details

Published
2022-04-29

Frequently asked questions

What is CVE-2021-4206?

A flaw was found in the QXL display device emulation in QEMU. An integer overflow in the cursor_alloc() function can lead to the allocation of a small cursor object followed by a subsequent heap-based buffer overflow. This flaw allows a malicious privileged guest user to crash the QEMU process on the host or potentially execute arbitrary code within the context of the QEMU process.

Is CVE-2021-4206 actively exploited?

Active exploitation of CVE-2021-4206 has not been confirmed. Its EPSS score was 0.8% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-4206?

CVE-2021-4206 has a CVSS v3 base score of 8.2 (HIGH severity).

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