Bug 2024628 (CVE-2021-3996) - CVE-2021-3996 util-linux: Unauthorized unmount of filesystems in libmount
Summary: CVE-2021-3996 util-linux: Unauthorized unmount of filesystems in libmount
Keywords:
Status: CLOSED WONTFIX
Alias: CVE-2021-3996
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2032273 2044307
Blocks: 2024641
TreeView+ depends on / blocked
 
Reported: 2021-11-18 14:20 UTC by Pedro Sampaio
Modified: 2023-09-15 01:50 UTC (History)
19 users (show)

Fixed In Version: util-linux 2.37.3
Doc Type: If docs needed, set a value
Doc Text:
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.
Clone Of:
Environment:
Last Closed: 2022-05-17 15:16:47 UTC
Embargoed:

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Description Pedro Sampaio 2021-11-18 14:20:47 UTC 
A flaw was found in util-linux's libmount. An issue related to parsing the /proc/self/mountinfo file allows an unprivileged user to unmount other users' filesystems that are either world-writable themselves (like /tmp) or mounted in a world-writable directory.
Comment 6 Riccardo Schirone 2021-11-19 16:09:56 UTC 
RHEL 6, 7 and 8 are not affected by this bug as they ship an older version of util-linux which does not allow unprivileged users to unmount FUSE mount points for the current user (e.g. is_fuse_usermount() function does not exist).
Comment 12 Riccardo Schirone 2022-01-24 11:08:40 UTC 
Upstream patch:
https://github.com/util-linux/util-linux/commit/166e87368ae88bf31112a30e078cceae637f4cdb
Comment 13 Riccardo Schirone 2022-01-24 11:10:06 UTC 
Release notes:
https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes
Comment 14 Riccardo Schirone 2022-01-24 12:01:37 UTC 
Created util-linux tracking bugs for this issue:

Affects: fedora-all [bug 2044307]
Comment 16 Product Security DevOps Team 2022-05-17 15:16:44 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-3996
Comment 17 Red Hat Bugzilla 2023-09-15 01:50:04 UTC 
The needinfo request[s] on this closed bug have been removed as they have been unresolved for 365 days
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