CVE-2021-3732

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-03-10 · updated 2026-06-17
Weakness: CWE-200

Description

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.

Affected products

Linux kernel: before 5.14; 5.14, 5.14-rc1, 5.14-rc2, 5.14-rc3, 5.14-rc4, 5.14-rc5 — fixed in 5.14

How to fix

Upgrade to a fixed version: Linux kernel 5.14. Check the vendor advisory for mitigations.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1995249
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=427215d85e8d1476da1a86b8d67aceb485eb3631
https://github.com/torvalds/linux/commit/427215d85e8d1476da1a86b8d67aceb485eb3631
https://ubuntu.com/security/CVE-2021-3732
https://bugzilla.redhat.com/show_bug.cgi?id=1995249
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=427215d85e8d1476da1a86b8d67aceb485eb3631
https://github.com/torvalds/linux/commit/427215d85e8d1476da1a86b8d67aceb485eb3631
https://ubuntu.com/security/CVE-2021-3732

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