Vulnerability

CVE-2021-3493

High· 8.8KEVEXPLOITCVSS8.8EPSS80%

.rules3/5

Linux Kernel Privilege Escalation Vulnerability

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.

Threat signal

100/100

Severe

Severity

high

CVSS

8.8

EPSS

80%

Active

KEV

CISA KEV — actively exploited

1311d overdue

AffectedLinux — Kernel

Added to KEV

2022-10-20

Federal patch due (BOD 22-01)

2022-11-10

Required action (CISA verbatim)

Apply updates per vendor instructions.

Vendor advisory + references

CISA description: “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.”

CVSS

v3.1Open in FIRST calculator →

8.8/ 10HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Attack VectorLocalRequires local access — shell, console, or local app.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredLowStandard user privileges sufficient.
User InteractionNoneFully automated — no victim action needed.
ScopeChangedImpact extends beyond the vulnerable component (e.g. sandbox escape).
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

80.0%

probability of exploitation in next 30 days

p99

higher than 99% of all CVEs

3-day trend↑ 0pp

Statistically about to be weaponized — top-tier triage urgency.

Vendor VEX

No VEX statements published for CVE-2021-3493. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: yes
impact: total
mission: support

Lifecycle

2022-10-20Added to CISA KEVransomware: Unknown
2022-10-20Public exploit observedmetasploit
2022-10-20Published
2022-11-10Federal patch due (BOD 22-01)
2026-06-12Last modified1 source

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.