CVE-2021-3493

highpriority · act · 90OT risk · criticalKEV · exploitedEPSS 0.492 · 99 %ileexploit · weaponizedEURUUS

grimoire priorityP0 · Act now

Exploitable?

Yes · in the wild

CISA KEV · 21 exploits · weaponized

Likely / severe?

49.2% (99th) EPSS

CVSS 7.2 · high

Is it mine?

13 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

added 2022-10-20remediate by 2022-11-10

required action Apply updates per vendor instructions.

EPSS · scored 2026-10-26

Linux Kernel Privilege Escalation Vulnerability

The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.

cvss

Technical severity, 0–10. One row per scoring source.

8.8

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.07.2highAV:L/AC:L/Au:N/C:C/I:C/A:Cprimary · NVD / NIST USexploitability 3.9 · impact 10

v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 1.8 · impact 5.9

v3.17.8highAV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.18.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Hsecondary · ENISA EU

v3.18.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Hsecondary · security@ubuntu.comexploitability 2 · impact 6

v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:Hsecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: active · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-863USprimaryCWE-269USCWE-270US

exploits (21)

Public proof-of-concept and weaponised exploit code.

affected products (13)

Products and version ranges known to be affected.

Ubuntu Linux kernel4.15 kernel → 4.15.0-142.146enisa_euvdEU
Ubuntu Linux kernel4.4 kernel → 4.4.0-209.241enisa_euvdEU
Ubuntu Linux kernel5.4 kernel → 5.4.0-72.80enisa_euvdEU
Ubuntu Linux kernel5.8 kernel → 5.8.0-50.56enisa_euvdEU
АО «НППКТ» ОСОН ОСнова Оnyx≤ 2.4fstec_bduRU
ООО «РусБИТех-Астра» Astra Linux Special Edition≤ 1.6 «Смоленск»fstec_bduRU
Сообщество свободного программного обеспечения Debian GNU/Linux≤ 9fstec_bduRU
Сообщество свободного программного обеспечения Debian GNU/Linux≤ 11fstec_bduRU
Сообщество свободного программного обеспечения Debian GNU/Linux≤ 10fstec_bduRU
Сообщество свободного программного обеспечения Linux≤ 5.11fstec_bduRU
canonical ubuntu linux< 18.04nvdUScpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:*:*:*:*
canonical ubuntu linux< 20.10nvdUScpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:*:*:*:*
canonical ubuntu linux18.04.1 → 20.04nvdUScpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:*:*:*:*

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd NVD CVE.org MITRE

published 2021-04-17modified 2026-06-17

related (4,997)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2026-71362US	—OT critical	90.5% (100th)	KEV	2026-08-11
Adobe Commerce is affected by an Incorrect Authorization vulnerability that could result in privilege escalation. An attacker could leverage this vulnerability to gain elevated acc…
CVE-2026-42016US	high8.8OT critical	8.64% (95th)	KEV	2026-07-27
JFrog Artifactory (Self Hosted) versions before 7.133.11 are vulnerable to a privilege escalation attack due to a validation check of the token signature/issuer and not the token’s…
CVE-2025-55177US	—OT critical	13.1% (96th)	KEV	2025-08-29
Incomplete authorization of linked device synchronization messages in WhatsApp for iOS prior to v2.25.21.73, WhatsApp Business for iOS v2.25.21.78, and WhatsApp for Mac v2.25.21.78…
CVE-2025-54253US	—OT critical	88.8% (100th)	KEV	2025-08-05
Adobe Experience Manager versions 6.5.23 and earlier are affected by a Misconfiguration vulnerability that could result in arbitrary code execution. An attacker could leverage this…
CVE-2025-21479US	—OT critical	0.84% (58th)	KEV	2025-06-03
Memory corruption due to unauthorized command execution in GPU micronode while executing specific sequence of commands.

+4992 more

references (27)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan