CVE-2021-3493
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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…
rank 73 = 40 + 20 + 2 + 5 + 6
rank@v1 · act now
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.49166 · CISA KEV listed · without this subject the record ranks 33
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 7.8, from NVD · without this subject the record ranks 53
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
rose on 2025-11-18 · without this subject the record ranks 71
How much of the world it touches
NVD CPE configurations
3 products in the CPE ranges · without this subject the record ranks 68
Someone else already set the date
CISA KEV remediation due date
CISA remediation date held · without this subject the record ranks 67
$2.45M = $4.99M incident cost x 1 exposure x 0.49166 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.
Sources disagree here.
Both shown, dated. We don't pick winners. disagreement-rules@v1
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Harm, if it fires from the vector and the weakness
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CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Exploited in the wild · CISA KEV listed, 2022-10-20.
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
Attack path
What it is stated by the CNA
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. receipt
NVD's analysis a second authority
- severity
- 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- weakness
- CWE-270; CWE-863
- affected versions
- canonical ubuntu linux < 18.04; canonical ubuntu linux >= 18.04.1 < 20.04; canonical ubuntu linux < 20.10
- also scored by
- [email protected] 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
The CNA scored it 8.8 and NVD 7.8. Both are shown because both were published; we do not pick one.
check it yourself ubuntu.com git.kernel.org openwall.com packetstormsecurity.com packetstormsecurity.com packetstormsecurity.com receipt
Dated events
Movement the material steps
This score more than doubled inside 72 hours. Both observations are in the full history below.
Show all 90 observations
90 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
Listed by CISA 551 days after it published, exploit probability more than doubled between 2021-04-17 and 2021-04-20 (0.00833 → 0.0363) and the record had been public for 5 years, 4 months when this index was last written.
No material movement in 37 days as of the last ingest this index recorded.
Siblings and hubs
Records related to this one
None. No alias set, and nothing in the corpus cites this identifier or shares its product family within 60 days.
Browse the index from here
These are index-wide views, not findings about CVE-2021-3493.
What usually comes next
Everything above needs no account. What is below is work: assembling it, scoping it to your estate, watching it, and handing it to someone else.