CVE-2026-12505
Publication date 18 June 2026
Last updated 4 July 2026
Ubuntu priority
Description
A flaw was found in the cifs-utils package where the cifs.upcall helper fails to securely drop its root privileges before looking up user information inside a user-controlled environment. A local, low privileged attacker can exploit this by using a crafted request_key payload to trick the root-owned helper into entering a custom environment (namespace) containing a malicious NSS module. This forces the system to load the attacker's controlled NSS Module and configuration, allowing them to execute arbitrary commands as the root user, elevating their privileges and fully compromising the system.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| cifs-utils | 26.04 LTS resolute |
Vulnerable
|
| 25.10 questing |
Vulnerable
|
|
| 24.04 LTS noble |
Vulnerable
|
|
| 22.04 LTS jammy |
Vulnerable
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
Notes
mdeslaur
The update for this issue introduced a regression, see: https://bugs.launchpad.net/ubuntu/+source/cifs-utils/+bug/2159053 https://lore.kernel.org/linux-cifs/16d7db05ac86fa6c7820c0f4996a3fcf@manguebit.org/T/#t The security fixed was backed out in USN-8496-2 until a complete fix is available from cifs-utils developers
Patch details
| Package | Patch details |
|---|---|
| cifs-utils |
Severity score breakdown
CVSS version: CVSS v3.0
Base score
7.8 · High
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
Related Ubuntu Security Notices (USN)
- USN-8496-1
- cifs-utils vulnerability
- 2 July 2026