CVE-2021-3975
CWE-416Published: August 23, 2022· Updated: Jun 17, 2026
Official 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.
Technical Analysis
CVE-2021-3975 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.
From a weakness classification perspective (CWE-416): Use-after-free vulnerabilities involve accessing memory after it has been freed, often enabling arbitrary code execution.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (12)
Quick Facts
Related CVEs (CWE-416)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-3975 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts