Bug 1995249 (CVE-2021-3732) - CVE-2021-3732 kernel: overlayfs: Mounting overlayfs inside an unprivileged user namespace can reveal files
Summary: CVE-2021-3732 kernel: overlayfs: Mounting overlayfs inside an unprivileged us...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2021-3732
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: 1993131 1996405 1996406 2000964
Blocks: 1995250 2003966
TreeView+ depends on / blocked
 
Reported: 2021-08-18 16:53 UTC by Pedro Sampaio
Modified: 2022-09-27 14:21 UTC (History)
40 users (show)

Fixed In Version: kernel 5.14 rc6
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the Linux kernel’s OverlayFS subsystem in the way the user mounts the TmpFS filesystem with OverlayFS. This flaw allows a local user to gain access to hidden files that should not be accessible.
Clone Of:
Environment:
Last Closed: 2021-11-09 21:53:49 UTC
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2021:4140 0 None None None 2021-11-09 17:24:06 UTC
Red Hat Product Errata RHSA-2021:4356 0 None None None 2021-11-09 18:28:06 UTC

Description Pedro Sampaio 2021-08-18 16:53:59 UTC 
A flaw was found in the Linux kernels implementation of overlayfs where a local attacker with an unpriviledged account who has the ability to mount a filesystem can abuse a logic bug in the overlayfs code which can inadvertantly reveal files hidden in the orignal mount.


References:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=427215d85e8d
https://bugzilla.redhat.com/show_bug.cgi?id=1993131
Comment 6 juneau 2021-08-23 13:52:22 UTC 
Marking Hosted OCP 4.x affected/delegated. (3.x unaffected)
Comment 8 Petr Matousek 2021-09-03 12:16:03 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2000964]
Comment 9 Justin M. Forbes 2021-09-03 15:18:40 UTC 
This was fixed for Fedora with the 5.13.11 stable kernel update.
Comment 11 errata-xmlrpc 2021-11-09 17:24:03 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4140 https://access.redhat.com/errata/RHSA-2021:4140
Comment 12 errata-xmlrpc 2021-11-09 18:28:03 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4356 https://access.redhat.com/errata/RHSA-2021:4356
Comment 13 Product Security DevOps Team 2021-11-09 21:53:45 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-2021-3732
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