vciy

CVE-2021-3930

INDEX BUILT · 2026-09-20

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An off-by-one error was found in the SCSI device emulation in QEMU

CVE-2021-39304 of 4 sources documented this
24

rank 24 = 0 + 16 + 0 + 8 + 0

rank@v1 · backlog

Someone is already using it

CISA KEV catalog · public proof-of-concept · FIRST EPSS

EPSS 0.00338  ·  without this subject the record ranks 24

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 6.5, from NVD  ·  without this subject the record ranks 8

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

no persisting rise in 365 days  ·  without this subject the record ranks 24

How much of the world it touches

NVD CPE configurations

12 products in the CPE ranges  ·  without this subject the record ranks 16

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 24

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$10,300over the next 30 days, if this record is yours
Movementno material movementthe record holds only daily drift and scoring model releases
Basisassumeda published average, not your estate

$10,300 = $4.99M incident cost x 0.6121449559255632 exposure x 0.00338 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

0.00338EPSSNOT IN KEVas of 2026-09-20
Severity6.5 MEDIUMreceipt
Harmpartial impactreceipt
Exploitationnone in held sources
Defenseunaffected versions publishedreceipt
Movementfallenreceipt
PLATEAU10Minimal movement since 2022-02-19, 1581 days at 0.00, as of 2026-06-19. arc-rules@v1

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.

Color is a claim, not decoration:the hostile worldthe defenseno signal

Running QEMU? Check your version

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Harm, if it fires from the vector and the weakness

Written for the ticket you're about to file.

Reachneeds local access · low privileges required · no user interaction · low attack complexityreceipt
ImpactComplete availability loss, with impact beyond the vulnerable componentreceipt
Scored fromCVSS v3.1 · NVD's vectorreceipt
Weakness classCWE-193 Off-by-one Errorreceipt
Published consequencesCWE-193: Availability: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory), DoS: Instability; Integrity: Modify Memory…[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

The fix, and how long it's been waiting.

First unaffected version, by branchqemu 6.2.0receipt
Patch available sinceNo dated patch-availability record in held sources. The index holds reference URLs without dates and only the current revision of the CVE record, so the day a fix first existed cannot be derived. Only the versions it landed in.

Exploit Status & Known PoCs a ladder, not a score

Current rung: Nothing observed in held sources.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, NVD6.5 MEDIUMreceipt
Exploit probability0.00338 · top 73% of all CVEsreceipt
Blast breadth10 products across 3 vendorsderived
Assigned byredhatreceipt
Recorded changes21 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productQEMUreceipt
Published rangesqemu < 6.2.0; redhat codeready linux builder 8.0; redhat codeready linux builder for ibm z systems 8.0; redhat codeready linux builder for power little endian 8.0receipt
Show all 12 published ranges
qemu < 6.2.0
redhat codeready linux builder 8.0
redhat codeready linux builder for ibm z systems 8.0
redhat codeready linux builder for power little endian 8.0
redhat openstack 10
redhat openstack 13
redhat enterprise linux 8.0
redhat enterprise linux advanced virtualization eus 8.4
redhat enterprise linux for ibm z systems 8.0
redhat enterprise linux for power little endian 8.0
debian linux 9.0
debian linux 10.0

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.

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What it is stated by the CNA

An off-by-one error was found in the SCSI device emulation in QEMU. It could occur while processing MODE SELECT commands in mode_sense_page() if the 'page' argument was set to MODE_PAGE_ALLS (0x3f). A malicious guest could use this flaw to potentially crash QEMU, resulting in a denial of service condition. receipt

NVD's analysis a second authority

severity
6.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
weakness
CWE-193
affected versions
qemu < 6.2.0; redhat codeready linux builder 8.0; redhat codeready linux builder for ibm z systems 8.0; and 9 more, listed in full below

check it yourself bugzilla.redhat.com security.netapp.com lists.debian.org security.gentoo.org lists.debian.org receipt

Movement the material steps

19 Feb 20220.00885
7 Mar 20234.2e-4 · scoring model v2023.03.01
17 Mar 20250.00024 · scoring model v2025.03.14
15 Jun 20260.0033 · scoring model v2026.06.15
19 Jun 20260.00338
Show all 21 observations
19 Feb 20220.00885
5 Apr 20220.0089
15 Aug 20220.0095
7 Mar 20234.2e-4
8 Mar 20230.00042
26 May 20230.00045
17 Mar 20250.00024
23 Mar 20250.00023
29 Mar 20250.00031
30 Mar 20250.00023
14 Apr 20250.00031
21 Jun 20250.00032
4 Jul 20250.00035
9 Jul 20250.00033
28 Jul 20250.00038
6 Oct 20250.00035
18 Nov 20250.00058
21 Nov 20250.00035
3 Dec 20250.00054
15 Jun 20260.0033
19 Jun 20260.00338

21 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

EPSS 0.00338Published2022-02-18Index as of2026-06-19

The record had been public for 4 years, 4 months when this index was last written.

Published 2022-02-18 receipt · Index as of 2026-06-19 derived

Siblings and hubs

Records related to this one

Its defect family

qemu

Grouped by shared product and weakness, not by shared vulnerability. Each record's own state is on its own page.

Family membership: held values

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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.

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