CVE-2021-3996
First published: Thu Nov 18 2021(Updated: )
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.
Credit: secalert@redhat.com secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/util-linux | <2.37.3 | 2.37.3 |
| >=2.34<2.37.3 | ||
| =35 | ||
| Kernel Util-linux | >=2.34<2.37.3 | |
| Fedoraproject Fedora | =35 |
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Reference Links
- https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes
- https://github.com/util-linux/util-linux/commit/166e87368ae88bf31112a30e078cceae637f4cdb
- https://www.openwall.com/lists/oss-security/2022/01/24/2
- https://bugzilla.redhat.com/show_bug.cgi?id=2024628
- https://access.redhat.com/security/cve/CVE-2021-3996
- http://www.openwall.com/lists/oss-security/2022/11/30/2
- http://seclists.org/fulldisclosure/2022/Dec/4
- http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perms-Race-Condition.html
- https://security.netapp.com/advisory/ntap-20221209-0002/
- https://security.gentoo.org/glsa/202401-08
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2044307
- https://access.redhat.com/security/cve/cve-2021-3996
Frequently Asked Questions
What is the vulnerability ID?
The vulnerability ID is CVE-2021-3996.
What is the title of the vulnerability?
The title of the vulnerability is '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.'
What is the severity of CVE-2021-3996?
The severity of CVE-2021-3996 is medium, with a severity value of 5.5.
What is the affected software?
The affected software includes Kernel Util-linux version 2.34 to 2.37.3, Fedoraproject Fedora version 35, and redhat/util-linux version up to 2.37.3.
How can this vulnerability be exploited?
This vulnerability can be exploited by a local user on a vulnerable system to unmount other users' filesystems that are either world-writable themselves or mounted in a specific way.
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