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Vulnerability record · CVE-2021-3975 · published 23 August 2022

CVE-2021-3975: Redhat libvirt use after free vulnerability

Redhat · Libvirt

A use-after-free flaw was found in libvirt. The qemuMonitorUnregister() function in qemuProcessHandleMonitorEOF is called using multiple threads without being adequately protected by a monitor lock. This flaw could be triggered by the virConnectGetAllDomainStats API when the guest is shutting down. An unprivileged client with a read-only connection could use this flaw to perform a denial of service attack by causing the libvirt daemon to crash.

6.5 CVSS 3.1 Medium EPSS 1.5% · top 26.1% CWE-416 · Use after free
6.5CVSS 3.1 base score
1.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
14Affected product versions listed by NVD
12References
17 Jun 2026Last modified by NVD

Description

A use-after-free flaw was found in libvirt. The qemuMonitorUnregister() function in qemuProcessHandleMonitorEOF is called using multiple threads without being adequately protected by a monitor lock. This flaw could be triggered by the virConnectGetAllDomainStats API when the guest is shutting down. An unprivileged client with a read-only connection could use this flaw to perform a denial of service attack by causing the libvirt daemon to crash.

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

Affected products

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

References

LinkTags
https://access.redhat.com/security/cve/CVE-2021-3975 Issue TrackingThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2024326 Issue TrackingPatchThird Party Advisory
https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2024/04/msg00000.html
https://security.netapp.com/advisory/ntap-20221201-0002/ Third Party Advisory
https://ubuntu.com/security/CVE-2021-3975 PatchThird Party Advisory
https://access.redhat.com/security/cve/CVE-2021-3975 Issue TrackingThird Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2024326 Issue TrackingPatchThird Party Advisory
https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2024/04/msg00000.html
https://security.netapp.com/advisory/ntap-20221201-0002/ Third Party Advisory
https://ubuntu.com/security/CVE-2021-3975 PatchThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-3975), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.