How severe is CVE-2021-3492?

CVE-2021-3492 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-3492 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3492?

CVE-2021-3492 primarily affects Canonical Ubuntu Linux. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3492?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-3492 published?

CVE-2021-3492 was published on 2021-04-17 and last updated on 2026-06-17.

CVE-2021-3492

CVE-2021-3492 is a high-severity vulnerability in Canonical Ubuntu Linux with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-401.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 7.2
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-401
Affected product: Canonical Ubuntu Linux
Published: 2021-04-17
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-3492?: 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.
How severe is CVE-2021-3492?: CVE-2021-3492 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-3492 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3492?: CVE-2021-3492 primarily affects Canonical Ubuntu Linux. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3492?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-3492 published?: CVE-2021-3492 was published on 2021-04-17 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:-:*:*:*

More vulnerabilities in Canonical Ubuntu Linux

CVE-2023-1523 — Critical (CVSS 10.0): Using the TIOCLINUX ioctl request, a malicious snap could inject contents into the input of the controlling terminal…
CVE-2020-13753 — Critical (CVSS 10.0): The bubblewrap sandbox of WebKitGTK and WPE WebKit, prior to 2.28.3, failed to properly block access to CLONE_NEWUSER…
CVE-2018-18505 — Critical (CVSS 10.0): An earlier fix for an Inter-process Communication (IPC) vulnerability, CVE-2011-3079, added authentication to…
CVE-2017-16845 — Critical (CVSS 10.0): hw/input/ps2.c in Qemu does not validate 'rptr' and 'count' values during guest migration, leading to out-of-bounds…
CVE-2016-0494 — Critical (CVSS 10.0): Unspecified vulnerability in the Java SE and Java SE Embedded components in Oracle Java SE 6u105, 7u91, and 8u66 and…
CVE-2016-0483 — Critical (CVSS 10.0): Unspecified vulnerability in Oracle Java SE 6u105, 7u91, and 8u66; Java SE Embedded 8u65; and JRockit R28.3.8 allows…

All CVEs affecting Canonical Ubuntu Linux →

Other CWE-401 (Missing Release of Memory after Effective Lifetime) vulnerabilities

CVE-2022-0742 — Critical (CVSS 9.1): Memory leak in icmp6 implementation in Linux Kernel 5.13+ allows a remote attacker to DoS a host by making it go…
CVE-2024-25450 — High (CVSS 8.8): imlib2 v1.9.1 was discovered to mishandle memory allocation in the function init_imlib_fonts().
CVE-2023-33718 — High (CVSS 8.8): mp4v2 v2.1.3 was discovered to contain a memory leak via MP4File::ReadString() at mp4file_io.cpp
CVE-2021-40633 — High (CVSS 8.8): A memory leak (out-of-memory) in gif2rgb in util/gif2rgb.c in giflib 5.1.4 allows remote attackers trigger an out of…
CVE-2019-17340 — High (CVSS 8.8): An issue was discovered in Xen through 4.11.x allowing x86 guest OS users to cause a denial of service or gain…
CVE-2019-6128 — High (CVSS 8.8): The TIFFFdOpen function in tif_unix.c in LibTIFF 4.0.10 has a memory leak, as demonstrated by pal2rgb.

Browse all CWE-401 (Missing Release of Memory after Effective Lifetime) vulnerabilities →