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Vulnerability record · CVE-2021-3748 · published 23 March 2022

CVE-2021-3748: Qemu use after free vulnerability

Qemu · Qemu

A use-after-free vulnerability was found in the virtio-net device of QEMU. It could occur when the descriptor's address belongs to the non direct access region, due to num_buffers being set after the virtqueue elem has been unmapped. A malicious guest could use this flaw to crash QEMU, resulting in a denial of service condition, or potentially execute code on the host with the privileges of the QEMU process.

7.5 CVSS 3.1 High EPSS 0.52% · top 58.0% CWE-416 · Use after free
7.5CVSS 3.1 base score, v2 6.9
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
6Affected product versions listed by NVD
16References
17 Jun 2026Last modified by NVD

Description

A use-after-free vulnerability was found in the virtio-net device of QEMU. It could occur when the descriptor's address belongs to the non direct access region, due to num_buffers being set after the virtqueue elem has been unmapped. A malicious guest could use this flaw to crash QEMU, resulting in a denial of service condition, or potentially execute code on the host with the privileges of the QEMU process.

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected products

6 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=1998514 Issue TrackingPatchThird Party Advisory
https://github.com/qemu/qemu/commit/bedd7e93d01961fcb16a97ae45d93acf357e11f6 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html Mailing ListThird Party Advisory
https://lists.nongnu.org/archive/html/qemu-devel/2021-09/msg00388.html Mailing ListPatchThird Party Advisory
https://security.gentoo.org/glsa/202208-27 Third Party Advisory
https://security.netapp.com/advisory/ntap-20220425-0004/ Third Party Advisory
https://ubuntu.com/security/CVE-2021-3748 PatchThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1998514 Issue TrackingPatchThird Party Advisory
https://github.com/qemu/qemu/commit/bedd7e93d01961fcb16a97ae45d93acf357e11f6 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/04/msg00002.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html Mailing ListThird Party Advisory
https://lists.nongnu.org/archive/html/qemu-devel/2021-09/msg00388.html Mailing ListPatchThird Party Advisory
https://security.gentoo.org/glsa/202208-27 Third Party Advisory
https://security.netapp.com/advisory/ntap-20220425-0004/ Third Party Advisory
https://ubuntu.com/security/CVE-2021-3748 PatchThird Party Advisory

Track CVE-2021-3748 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

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Source: NIST National Vulnerability Database (record CVE-2021-3748), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.