CVE-2021-43566
Publication date 11 January 2022
Last updated 18 August 2025
Ubuntu priority
Description
All versions of Samba prior to 4.13.16 are vulnerable to a malicious client using an SMB1 or NFS race to allow a directory to be created in an area of the server file system not exported under the share definition. Note that SMB1 has to be enabled, or the share also available via NFS in order for this attack to succeed.
Mitigation
This issue can be mitigated by disabling SMB1, which is the default configuration in Samba 4.11 and above. In environments where SMB1 cannot be disabled, symlink support can be disabled with unix extensions = no.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| samba | 26.04 LTS resolute |
Fixed 4.13.17~dfsg-0ubuntu1
|
| 25.10 questing |
Fixed 4.13.17~dfsg-0ubuntu1
|
|
| 24.04 LTS noble |
Fixed 4.13.17~dfsg-0ubuntu1
|
|
| 22.04 LTS jammy |
Fixed 4.13.17~dfsg-0ubuntu1
|
|
| 20.04 LTS focal |
Fixed 2:4.13.17~dfsg-0ubuntu0.21.04.1
|
|
| 18.04 LTS bionic |
Vulnerable
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
Severity score breakdown
CVSS version: CVSS v3.0
Base score
2.5 · Low
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
References
Related Ubuntu Security Notices (USN)
- USN-5260-1
- Samba vulnerabilities
- 1 February 2022