CVE-2021-3975: canonical ubuntu_linux Use After Free
Vulnerability summary
CVE-2021-3975 is a medium (CVSS 6.5) Use After Free vulnerability in canonical ubuntu_linux. EPSS estimates a 1.64% chance of exploitation in the next 30 days, higher than 76.4% of scored vulnerabilities.
Not severe (CVSS 6.5, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 10 · Related 8Timeline
- 23-08-2022PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
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 metrics
4 scores · 4 sources · 1 version- OSV · Red hatEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
1.64%
Chance of exploitation in the next 30 days
Percentile
76%
Versus all other CVEs
30-day change
Increase +0.10 pp
From 1.54% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Redhat194 products
- codeready_linux_builderna
- enterprise_linux8.0
- enterprise_linux_eus8.6
- enterprise_linux_for_ibm_z_systems8.0
- enterprise_linux_for_ibm_z_systems_eus8.6
Debian2 products
- libvirt< 7.6.0-1
- debian_linuxEOL10.0 | 11.0
Canonical1 product
- ubuntu_linuxEOL21.10
Fedoraproject1 product
- fedoraEOL35
Netapp1 product
Ubuntu1 product
- libvirt< 4.0.0-1ubuntu8.21 | < 6.0.0-0ubuntu8.16 | < 7.6.0-0ubuntu3
6 vendors · 200 products · Showing 200 of 250
References
165 links- security.netapp.com/advisory/ntap-20221201-0002/Third Party Advisory
Show all 100 references
Showing 100 of 165.