vciy

CVE-2021-34478

INDEX BUILT · 2026-09-20

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Microsoft Office Remote Code Execution Vulnerability

CVE-2021-344784 of 4 sources documented this
32

rank 32 = 13 + 17 + 0 + 2 + 0

rank@v1 · scheduled

Someone is already using it

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

EPSS 0.51243  ·  without this subject the record ranks 19

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 6.8, from NVD  ·  without this subject the record ranks 15

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

1 product in the CPE ranges  ·  without this subject the record ranks 30

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$2.56Mover the next 30 days, if this record is yours
Movement-$120,000on 2025-08-23, the last material move, 1 year before this reading
Basisassumeda published average, not your estate

$2.56M = $4.99M incident cost x 1 exposure x 0.51243 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

0.51243EPSSNOT IN KEVas of 2026-09-20
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationnone in held sources
Defenseno fix version held
Movementdoubled within 72hreceipt
PLATEAU10Minimal movement since 2026-06-15, 74 days at 0.51, as of 2026-08-28. 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
Microsoft7.8 HIGHreceipt
NVD6.8 MEDIUMreceipt
Scoring standard
MicrosoftCVSS v3.1receipt
NVDCVSS v2.0receipt

Both shown, dated. We don't pick winners. disagreement-rules@v1

Running Microsoft 365 Apps for Enterprise? Check your version

A deterministic range check against the ranges this record publishes. It tells you where a version sits in the record, not whether your deployment is exploitable. No account needed.

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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 · no privileges required · user interaction required · low attack complexityreceipt
ImpactComplete confidentiality, integrity and availability lossreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classNo CWE mapping in held sources.

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 28 Aug 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 CNA7.8 HIGHreceipt
CVSS, NVD6.8 MEDIUMreceipt
Exploit probability0.51243 · top 1% of all CVEsreceipt
Blast breadth1 product across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes57 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productMicrosoft 365 Apps for Enterprise; Microsoft Office 2019receipt
Published rangesmicrosoft office 2019receipt

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.

Did this affect your environment?Answering needs an account.

What it is stated by the CNA

Microsoft Office Remote Code Execution Vulnerability receipt

NVD's analysis a second authority

severity
6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P
affected versions
microsoft office 2019
also scored by
[email protected] 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H · [email protected] 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

The CNA scored it 7.8 and NVD 6.8. Both are shown because both were published; we do not pick one.

check it yourself msrc.microsoft.com receipt

Dated events

2021-08-19EPSS moved 0.01 to 0.102026-06-15EPSS moved 0.09 to 0.54

Movement the material steps

13 Aug 20210.00918
27 Aug 20210.13741 · crossed 0.10
6 Jan 20220.41682
4 Feb 20220.3168
1 Apr 20220.04475 · crossed 0.10
7 Mar 20230.00226 · scoring model v2023.03.01
17 Mar 20250.10024 · crossed 0.10 · scoring model v2025.03.14
29 Mar 20250.2068
23 Aug 20250.09479 · crossed 0.10
15 Jun 20260.54383 · crossed 0.10 and 0.50 · scoring model v2026.06.15
28 Aug 20260.51243

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

Show all 57 observations
13 Aug 20210.00918
19 Aug 20210.09575
27 Aug 20210.13741
6 Jan 20220.41682
4 Feb 20220.3168
1 Apr 20220.04475
28 Feb 20230.04844
7 Mar 20230.00226
20 Mar 20230.00264
15 Jun 20230.00253
29 Jun 20230.00333
12 Jul 20230.00400
28 Jul 20230.00454
9 Aug 20230.00555
26 Aug 20230.00505
22 Sep 20230.00461
20 Oct 20230.00667
4 Nov 20230.00564
16 Nov 20230.00645
2 Dec 20230.00458
14 Dec 20230.00634
29 Dec 20230.00913
12 Jan 20240.00725
25 Jan 20240.02931
8 Feb 20240.00682
21 Feb 20240.02218
6 Mar 20240.01380
18 Mar 20240.01667
1 Apr 20240.02021
14 Apr 20240.01268
27 Apr 20240.01835
23 May 20240.01577
7 Jun 20240.01271
4 Jul 20240.01142
18 Jul 20240.01069
15 Aug 20240.01113
14 Sep 20240.01890
28 Sep 20240.01784
13 Oct 20240.01569
29 Oct 20240.04725
13 Nov 20240.01642
28 Nov 20240.05639
15 Dec 20240.00917
17 Dec 20240.01094
9 Mar 20250.01077
17 Mar 20250.10024
19 Mar 20250.10268
25 Mar 20250.12683
29 Mar 20250.2068
30 Mar 20250.12683
3 Jun 20250.1188
23 Aug 20250.09479
18 Nov 20250.04203
21 Nov 20250.09479
15 Jun 20260.54383
11 Aug 20260.52656
28 Aug 20260.51243

57 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 0.51243Published2021-08-12Index as of2026-08-28

Exploit probability more than doubled between 2025-11-18 and 2025-11-21 (0.04203 → 0.09479) and the record had been public for 5 years when this index was last written.

Published 2021-08-12 receipt · Index as of 2026-08-28 derived

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