Vulnerability in Kernel Util-Linux
CVE-2021-3996
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (50.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: +0.000
Affected products
- Kernel Util-Linux
- Fedoraproject Fedora — versions 35
- Util-Linux — versions Fixed in util-linux v2.37.3
Weakness classification (CWE)
Public proof-of-concept exploits
References
- mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes (Release Notes, Vendor Advisory)
- github.com/util-linux/util-linux/commit/166e87368ae88bf31112a30e078cceae637f4cdb (Patch, Third Party Advisory)
- www.openwall.com/lists/oss-security/2022/01/24/2 (Exploit, Patch, Mailing List, Third Party Advisory)
- bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
- access.redhat.com/security/cve/CVE-2021-3996 (Third Party Advisory, Issue Tracking)
- www.openwall.com/lists/oss-security/2022/11/30/2 (mailing-list, Mailing List, Third Party Advisory)
- seclists.org/fulldisclosure/2022/Dec/4 (mailing-list, Mailing List, Third Party Advisory)
- packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perm… (Third Party Advisory)
- security.netapp.com/advisory/ntap-20221209-0002/ (Third Party Advisory, Broken Link)
- security.gentoo.org/glsa/202401-08 (vendor-advisory)
Frequently asked questions
- What is CVE-2021-3996?
- CVE-2021-3996 is a medium-severity vulnerability in Kernel Util-Linux, classified under Files or Directories Accessible to External Parties. CVSS score: 5.5/10. Published 2022-08-23.
- How severe is CVE-2021-3996?
- Medium severity. CVSS v3 base score is 5.5 out of 10.
- Is CVE-2021-3996 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.