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CVE record · CVE-2021-3493

Ubuntu linux kernel: The overlayfs implementation in the linux kernel did not properly validate with respect…

CVSS 8.8 HighCriticalIn CISA KEVEPSS 0.49 · 98th percentile

Critical, because:

  • In CISA’s KEV catalogue since 20 Oct 2022: it is known to be exploited.
  • CVSS score 8.8 (7.0 or more) and EPSS 0.49 (0.1 or more): a high score and a real chance of exploitation in the next 30 days.

How we decide what’s critical

Published by the CVE Program (CNA: canonical) at 17 Apr 2021, 04:20 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
VendorProductVersions
Ubuntu linux kernel
  • affected 5.8 kernel to before 5.8.0-50.56 custom
  • affected 5.4 kernel to before 5.4.0-72.80 custom
  • affected 4.15 kernel to before 4.15.0-142.146 custom
  • affected 4.4 kernel to before 4.4.0-209.241 custom
Identifiers
CVE-2021-3493
CNA
canonical
Weakness (CWE)
CWE-270
Tags
Published
17 Apr 2021
Updated
21 Oct 2025

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.8 High 3.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H CNA (canonical)
  • CISA KEV Listed since 20 Oct 2022: known to be exploited.
  • EPSS 0.49, the 98th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 17 Apr 2021. New records show when each source confirmed them.

Sources

References from the CNA

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.