Page generated: 09 Nov 2026, 09:23 UTC
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CVE-2021-3493

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 kerne…

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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 8.8 (HIGH) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
1.8/10
REALITY · THREAT PRIORITY
8.6/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 8.8: +1.32
  • Fresh EPSS: 49.17%: +0.25

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Sources: 9 documents and public datasets.

Hype components

Headline sample (25%)
60/100
Press, 30 days (60%)
5/100
Grounded branding (15%)
0/100
HYPE TOTAL18/100

Sources and documents

SOCRadar
Press · 23 Oct 2026, 07:00 · AI-Assisted Cyberespio…ets Government Systems - SOCRadar
SOCRadar® Cyber Intelligence Inc.
Press · 02 Oct 2026, 07:00 · Lunex Uses BYOVD to Di…loy Persistent Stealer - SOCRadar® Cyber Intelligence Inc.
SOCRadar
Press · 21 Sep 2026, 07:00 · BlueMoon Exploit Kit R…le Espionage Campaigns - SOCRadar
wiz.io
Press · 27 Jul 2023, 07:00 · GameOverlay Vulnerability Impacts 40% of Ubuntu Workloads | Wiz Blog - wiz.io
The Hacker News
Press · 27 Jul 2023, 07:00 · GameOver(lay): Two Severe Linux Vulnerabilities Impact 40% of Ubuntu Users - The Hacker News
See all 9 source documents
SecurityWeek
Press · 27 Jul 2023, 07:00 · Two New Vulnerabilities Could Affect 40% of Ubuntu Cloud Workloads - SecurityWeek
Ars Technica
Press · 09 Sep 2022, 07:00 · New Linux malware combines unusual stealth with a full suite of capabilities - Ars Technica
Malwarebytes
Press · 07 Sep 2022, 07:00 · Evasive Shikitega Linux malware drops Monero cryptominer - Malwarebytes
BleepingComputer
Press · 06 Sep 2022, 07:00 · New Linux malware evades detection using multi-stage deployment - BleepingComputer

Score evolution

● Hype   ● Reality

Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.

First record: hype 1.8 · reality 8.6 (2026-11-02 15:12). The curve appears once the score changes.

Public exploit evidence

0

Public exploit entries / repo candidates

Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.

Evidence in context

Confidence in exploitation evidence
Exploitation recorded
Priority basis
Recorded exploitation; CVSS 8.8; EPSS 49.2%
Attention, last 30 days
1 distinct story titles; 1 press documents; 1 publisher domains.
Technical potential
local access, low privileges, no user interaction.
Observed activity
Exploitation recorded in CISA KEV.
Known scale
Not quantified.
Evidence confidence basis
Trusted exploitation confirmation

Score evaluated: 2026-11-05 13:58:27.921902+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
Published
17 Apr 2021, 04:20
First press mention
06 Sep 2022, 07:00
Added to the CISA KEV catalog
20 Oct 2022, 00:00
Latest press mention
23 Oct 2026, 07:00
Score calculated
05 Nov 2026, 13:58