CVE-2021-3492

Name: CVE-2021-3492
Creator: NVD / NIST
Published: 2021-04-17T05:15:13.113+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 1.55%

Last modified Jun 17, 2026

CVE-2021-3492 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. EPSS estimates a 1.55% chance of exploitation in the next 30 days.

Description

Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. An attacker could use this to cause a denial of service (kernel memory exhaustion) or gain privileges via executing arbitrary code. AKA ZDI-CAN-13562.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

1.55%

71.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Canonical	Ubuntu Linux	< 18.04
Canonical	Ubuntu Linux	>= 18.04.1, < 20.04
Canonical	Ubuntu Linux	< 20.10

References

http://packetstormsecurity.com/files/162614/Kernel-Live-Patch-Security-Notice-LSN-0077-1.htmlThird Party Advisory, VDB Entry
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=25c891a949bf918b59cbc6e4932015ba4c35c333Mailing List, Patch, Vendor Advisory
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=8fee52ab9da87d82bc6de9ebb3480fff9b4d53e6Mailing List, Patch, Vendor Advisory
https://ubuntu.com/security/notices/USN-4917-1Vendor Advisory
https://www.openwall.com/lists/oss-security/2021/04/16/2Mailing List, Third Party Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-422/Third Party Advisory, VDB Entry
http://packetstormsecurity.com/files/162614/Kernel-Live-Patch-Security-Notice-LSN-0077-1.htmlThird Party Advisory, VDB Entry
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=25c891a949bf918b59cbc6e4932015ba4c35c333Mailing List, Patch, Vendor Advisory
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=8fee52ab9da87d82bc6de9ebb3480fff9b4d53e6Mailing List, Patch, Vendor Advisory
https://ubuntu.com/security/notices/USN-4917-1Vendor Advisory
https://www.openwall.com/lists/oss-security/2021/04/16/2Mailing List, Third Party Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-422/Third Party Advisory, VDB Entry

Timeline

Published: Apr 17, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3492?

How severe is CVE-2021-3492?

CVE-2021-3492 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 1.55% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3492?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3492?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST