CVE-2021-3975
MEDIUMCVSS 6.5/10EPSS 1.22%
Last modified
CVE-2021-3975 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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. EPSS estimates a 1.22% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Redhat | Libvirt | < 7.1.0 |
| Canonical | Ubuntu Linux | 21.10 |
| Fedoraproject | Fedora | 35 |
| Redhat | 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 |
| Redhat | Codeready Linux Builder | All versions |
| Debian | Debian Linux | 10.0 |
| Debian | Debian Linux | 11.0 |
| Netapp | Ontap Select Deploy Administration Utility | All versions |
References
- https://access.redhat.com/security/cve/CVE-2021-3975Issue Tracking, Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2024326Issue Tracking, Patch, Third Party Advisory
- https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7Patch, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20221201-0002/Third Party Advisory
- https://ubuntu.com/security/CVE-2021-3975Patch, Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2021-3975Issue Tracking, Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2024326Issue Tracking, Patch, Third Party Advisory
- https://github.com/libvirt/libvirt/commit/1ac703a7d0789e46833f4013a3876c2e3af18ec7Patch, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20221201-0002/Third Party Advisory
- https://ubuntu.com/security/CVE-2021-3975Patch, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-3975?
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.
How severe is CVE-2021-3975?
CVE-2021-3975 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.22% probability of exploitation in the next 30 days.
How do I fix CVE-2021-3975?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-3975?
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Scan your code nowSource: NVD / NIST