CVE-2021-4145
Publication date 25 January 2022
Last updated 25 August 2025
Ubuntu priority
Description
A NULL pointer dereference issue was found in the block mirror layer of QEMU in versions prior to 6.2.0. The `self` pointer is dereferenced in mirror_wait_on_conflicts() without ensuring that it's not NULL. A malicious unprivileged user within the guest could use this flaw to crash the QEMU process on the host when writing data reaches the threshold of mirroring node.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| qemu | 22.04 LTS jammy |
Not affected
|
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic |
Not affected
|
|
| 16.04 LTS xenial |
Not affected
|
|
| 14.04 LTS trusty |
Not affected
|
Notes
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
6.5 · Medium
|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Changed |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | High |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H |