A logic error was found in the libmount library of util-linux in the function that allows…
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-552.
Summary
A logic error was found in the libmount library of util-linux in the function that allows an unprivileged user to unmount a FUSE filesystem. This flaw allows a local user on a vulnerable system to unmount other users' filesystems that are either world-writable themselves (like /tmp) or mounted in a world-writable directory. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | util-linux | Fixed in util-linux v2.37.3 | — | No fix listed | CNA |
- util-linux Vendor— Affected Fixed in util-linux v2.37.3 Fixed in — No fix listed CNA
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:kernel:util-linux:*:*:*:*:*:*:*:* | 2.34 to before 2.37.3 | Vulnerable | kernel |
| cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* | 35 | Vulnerable | Fedoraproject |
- cpe:2.3:a:kernel:util-linux:*:*:*:*:*:*:*:* Versions 2.34 to before 2.37.3 Vulnerable ·kernel
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 4 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2021-3996
- 2026-10-21 EPSS moved to the 50th–90th percentile
References
Patch 2
Advisory 7
- https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes
- https://access.redhat.com/security/cve/CVE-2021-3996
- [oss-security] 20221130 Race condition in snap-confine's must_mkdir_and_open_with_perms() (CVE-2022-3328)
- 20221208 Race condition in snap-confine's must_mkdir_and_open_with_perms() (CVE-2022-3328)
- http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perms-Race-Condition.html
- https://security.netapp.com/advisory/ntap-20221209-0002/
- GLSA-202401-08
Sources
- CVE-2021-3996 · CVE Program
- CVE-2021-3996 · NVD
- FIRST EPSS
- CVE-2021-3996 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences