What’s Vulnerable › Vulnerabilities
CVE-2021-3975
- Severity: medium (CVSS 6.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 1.6% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2022-08-23 · updated 2026-06-17
- Weakness: CWE-416
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.
Affected products
- Canonical Ubuntu Linux: 21.10
- Debian Linux: 10.0, 11.0
- Fedoraproject Fedora: 35
- NetApp ONTAP Select Deploy administration utility: all versions
- RedHat Codeready Linux Builder: all versions
- Red Hat Enterprise Linux: 8.0
- RedHat Enterprise Linux Eus: 8.6
- RedHat Enterprise Linux For Ibm Z Systems: 8.0
- RedHat Enterprise Linux For Ibm Z Systems Eus: 8.6
- RedHat Enterprise Linux For Power Little Endian: 8.0
- RedHat Enterprise Linux For Power Little Endian Eus: 8.6
- RedHat Enterprise Linux Server For Power Little Endian Update Services For Sap Solutions: 8.6
- RedHat Enterprise Linux Server Tus: 8.6
- libvirt: before 7.1.0 — fixed in 7.1.0
How to fix
Upgrade to a fixed version: libvirt 7.1.0. Check the vendor advisory for mitigations.
References
- https://access.redhat.com/security/cve/CVE-2021-3975
- https://bugzilla.redhat.com/show_bug.cgi?id=2024326
- https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7
- https://lists.debian.org/debian-lts-announce/2024/04/msg00000.html
- https://security.netapp.com/advisory/ntap-20221201-0002/
- https://ubuntu.com/security/CVE-2021-3975
- https://access.redhat.com/security/cve/CVE-2021-3975
- https://bugzilla.redhat.com/show_bug.cgi?id=2024326
- https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7
- https://lists.debian.org/debian-lts-announce/2024/04/msg00000.html
- https://security.netapp.com/advisory/ntap-20221201-0002/
- https://ubuntu.com/security/CVE-2021-3975
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