HIGHCVSS v3.1 7.8Actively exploited · CISA KEV since 2022-10-20Vulnerability

CVE-2021-3493

The overlayfs stacking file system in Linux kernel does not properly validate the application of file capabilities against user namespaces, which could lead to privilege escalation.

Properties

Euvd product
Linux kernel
Vulnerability name
Linux Kernel Privilege Escalation Vulnerability
First seen
2025-10-21T23:25:48+00:00
Cvss score
7.8
Epss score
0.49166
Last seen
2026-10-19T12:00:27+00:00
Due date
2022-11-10
Euvd assigner
canonical
Retrieved at
2026-10-21T01:24:47+00:00
Exploited euvd since
2022-10-20T00:00:00+00:00
Src batch id
epss_history-20261020T103617Z-728ddd
Source url
https://epss.empiricalsecurity.com/epss_scores-2026-10-19.csv.gz
Date added
2022-10-20
Score
7.8
Euvd base score version
3.1
Fetched at
2026-10-20T10:36:20+00:00
Euvd vendor
Ubuntu
Cvss vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
In Signal since
initial import (Sep 2026)
Euvd base score
8.8

Related Entities (10)

MENTIONED_IN (4)

→[Campaign]ClingSTUN Turns Vulnerable Edge Devices Into Attacker Infrastructure
→[Campaign]Lunex Uses BYOVD to Disable Security Monitoring and Deploy Persistent Stealer
→[Campaign]NightLedger Backdoor Deployed in Espionage Campaign Targeting the Middle East and Africa
→[Campaign]ClickFix-Themed Campaign Deploys Starland RAT and WLDR Framework

AFFECTS_PRODUCT (2)

→[Product]cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:-:*:*:*
→[Product]cpe:2.3:o:canonical:ubuntu_linux:*:*:*:*:lts:*:*:*

HAS_WEAKNESS (2)

→[Weakness]Incorrect Authorization
→[Weakness]CWE-270

DESCRIBES (1)

←[KEVEntry]Linux Kernel Privilege Escalation Vulnerability

INVOLVES (1)

←[Signal]kev_added · 2022-10-20

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CVE-2021-3493 (CVSS v3.1 7.8) — Ninja Signal Threat Intelligence | Ninja Signal