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CVE-2021-38578

INDEX BUILT · 2026-09-20

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Existing CommBuffer checks in SmmEntryPoint will not catch underflow when computing BufferSize.

CVE-2021-385784 of 4 sources documented this
32

rank 32 = 0 + 25 + 0 + 7 + 0

rank@v1 · scheduled

Someone is already using it

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

EPSS 0.01011  ·  without this subject the record ranks 32

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 9.8, from NVD  ·  without this subject the record ranks 7

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 32

How much of the world it touches

NVD CPE configurations

7 products in the CPE ranges  ·  without this subject the record ranks 25

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 32

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$46,800over 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

$46,800 = $4.99M incident cost x 0.9280467328949208 exposure x 0.01011 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

0.01011EPSSNOT IN KEVas of 2026-09-20
Severity7.4 HIGHreceipt
Harmpartial impactreceipt
Exploitationnone in held sources
Defenseno fix version held
Movementdoubled within 72hreceipt
PLATEAU10Minimal movement since 2022-03-04, 1602 days at 0.01, as of 2026-07-23. 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

Sources disagree here.

Severity score
TianoCore7.4 HIGHreceipt
NVD9.8 CRITICALreceipt
What it costs
TianoCoreComplete confidentiality and integrity loss; partial availability loss, with impact beyond the vulnerable componentreceipt
NVDComplete confidentiality, integrity and availability lossreceipt

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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Reachneeds local access · high privileges required · no user interaction · high attack complexityreceipt
ImpactComplete confidentiality and integrity loss; partial availability loss, with impact beyond the vulnerable componentreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classCWE-124 Buffer Underwrite ('Buffer Underflow')receipt
Published consequencesCWE-124: Integrity, Availability: Modify Memory, DoS: Crash, Exit, or Restart; Integrity, Confidentiality, Availability, Access Control, Other: Execute Unauthorized Code or Commands, Modify Memory…[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

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

Fixed inNo fix version in held sources, as the index stood on 23 Jul 2026.
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, the CNA7.4 HIGHreceipt
CVSS, NVD9.8 CRITICALreceipt
Exploit probability0.01011 · top 38% of all CVEsreceipt
Blast breadth2 products across 2 vendorsderived
Assigned byTianoCorereceipt
Recorded changes42 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productTianoCore EDK IIreceipt
Published rangestianocore edk2 <= 202202; insyde kernel 5.0; insyde kernel 5.1; insyde kernel 5.2receipt
Show all 7 published ranges
tianocore edk2 <= 202202
insyde kernel 5.0
insyde kernel 5.1
insyde kernel 5.2
insyde kernel 5.3
insyde kernel 5.4
insyde kernel 5.5

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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Attack path

Local accessrequires high privilegesTianoCore EDK IICWE-124 weaknessAdjacent componentsscope changeConfidentiality and integrity lossC:H / I:Hexploits CWE-124scope changedata compromise

What it is stated by the CNA

Existing CommBuffer checks in SmmEntryPoint will not catch underflow when computing BufferSize. receipt

NVD's analysis a second authority

severity
9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
weakness
CWE-124; CWE-787
affected versions
tianocore edk2 <= 202202; insyde kernel 5.0; insyde kernel 5.1; and 4 more, listed in full below
also scored by
[email protected] 7.4 CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:L

The CNA scored it 7.4 and NVD 9.8. Both are shown because both were published; we do not pick one.

check it yourself bugzilla.tianocore.org insyde.com receipt

Movement the material steps

4 Mar 20220.00885
7 Mar 20239.1e-4 · scoring model v2023.03.01
17 Mar 20250.00061 · scoring model v2025.03.14
15 Jun 20260.00979 · scoring model v2026.06.15
23 Jul 20260.01011

This score more than doubled inside 72 hours. Both observations are in the full history below.

Show all 42 observations
4 Mar 20220.00885
7 Mar 20239.1e-4
8 Mar 20230.00091
10 Mar 20230.00143
8 May 20230.00142
23 Jul 20230.00157
14 Aug 20230.00179
24 Sep 20230.00185
16 Nov 20240.00205
17 Dec 20240.00235
17 Mar 20250.00061
19 Mar 20250.00196
20 Mar 20250.00061
21 Mar 20250.00071
22 Mar 20250.00069
27 Mar 20250.00222
28 Mar 20250.00069
29 Mar 20250.00222
30 Mar 20250.00069
7 Jun 20250.00051
13 Jun 20250.00052
27 Jun 20250.00051
4 Jul 20250.00054
22 Jul 20250.00051
28 Jul 20250.00061
30 Jul 20250.00051
10 Aug 20250.00058
16 Sep 20250.00059
21 Sep 20250.00058
4 Nov 20250.00064
18 Nov 20250.00241
21 Nov 20250.00064
18 Jan 20260.00066
26 Jan 20260.00064
27 Jan 20260.00077
18 Feb 20260.00079
19 Feb 20260.00077
1 Mar 20260.00064
15 Jun 20260.00979
27 Jun 20260.00971
2 Jul 20260.00995
23 Jul 20260.01011

42 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 0.01011Published2022-03-03Index as of2026-07-23

Exploit probability more than doubled between 2025-03-17 and 2025-03-19 (0.00061 → 0.00196) and the record had been public for 4 years, 4 months when this index was last written.

Published 2022-03-03 receipt · Index as of 2026-07-23 derived

Siblings and hubs

Records related to this one

Its defect family

tianocore edk ii

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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