vciy

CVE-2021-34518

INDEX BUILT · 2026-09-20

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Microsoft Excel Remote Code Execution Vulnerability

CVE-2021-345184 of 4 sources documented this
23

rank 23 = 1 + 17 + 0 + 5 + 0

rank@v1 · backlog

Someone is already using it

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

EPSS 0.02332  ·  without this subject the record ranks 22

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 6

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 23

How much of the world it touches

NVD CPE configurations

3 products in the CPE ranges  ·  without this subject the record ranks 18

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 23

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$116,000over the next 30 days, if this record is yours
Movement-$597,000on 2024-10-30, the last material move, 1 year, 9 months before this reading
Basisassumeda published average, not your estate

$116,000 = $4.99M incident cost x 1 exposure x 0.02332 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

0.02332EPSSNOT IN KEVas of 2026-09-20
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationnone in held sources
Defensefix version namedreceipt
Movementrisenreceipt
PLATEAU10Minimal movement since 2024-10-30, 650 days at 0.02, as of 2026-08-11. 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 Excel 2013 Service Pack 1? 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.

Watch this record

Matches your own product list against every record this index holds, and tells you when one of them moves.

What counts as a move

Set up a watchlist (needs a Practitioner account)

Record your call

Keep your verdict, your reason and the evidence together. The record takes its date when you save it.

AcceptDeferPatch by…Not affectedMitigated

Choose your verdict, then sign in or use an email link. Your first 100 records are free. Evidence is frozen when the record is created.

Private to your organization unless you share it. Put the proof link in your ticket so a reviewer can inspect the basis for your call. See how decision records work.

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 in15.0.5363.1000; 16.0.5188.100receipt
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 probability0.02332 · top 17% of all CVEsreceipt
Blast breadth2 products across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes66 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productMicrosoft Excel 2013 Service Pack 1; Microsoft Excel 2016; Microsoft Office Web Apps Server 2013 Service Pack 1receipt
Published rangesmicrosoft excel 2013; microsoft excel 2016; microsoft office web apps server 2013receipt
Fixed in15.0.5363.1000; 16.0.5188.100receipt

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 Excel 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 excel 2013; microsoft excel 2016; microsoft office web apps server 2013
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

2021-07-21EPSS moved 0.01 to 0.102023-12-27EPSS moved 0.02 to 0.382024-10-30EPSS moved 0.13 to 0.01

Movement the material steps

15 Jul 20210.00918
6 Jan 20220.32208 · crossed 0.10
4 Feb 20220.12761
1 Apr 20220.01528 · crossed 0.10
7 Mar 20230.00496 · scoring model v2023.03.01
30 Nov 20230.27533 · crossed 0.10
14 Dec 20230.02309 · crossed 0.10
27 Dec 20230.38247 · crossed 0.10
10 Jan 20240.02876 · crossed 0.10
12 Apr 20240.15220 · crossed 0.10
24 Apr 20240.04080 · crossed 0.10
19 Jun 20240.10568 · crossed 0.10
2 Jul 20240.04452 · crossed 0.10
17 Jul 20240.10351 · crossed 0.10
31 Jul 20240.06521 · crossed 0.10
16 Aug 20240.27661 · crossed 0.10
30 Aug 20240.10070
30 Sep 20240.07927 · crossed 0.10
15 Oct 20240.13299 · crossed 0.10
30 Oct 20240.01331 · crossed 0.10
17 Mar 20250.00527 · scoring model v2025.03.14
15 Jun 20260.02151 · scoring model v2026.06.15
11 Aug 20260.02332
Show all 66 observations
15 Jul 20210.00918
21 Jul 20210.09575
6 Jan 20220.32208
4 Feb 20220.12761
1 Apr 20220.01528
2 Oct 20220.01648
30 Jan 20230.01789
7 Mar 20230.00496
19 Mar 20230.00695
3 Apr 20230.00527
3 May 20230.00626
17 May 20230.00437
31 May 20230.00213
29 Jun 20230.00239
10 Aug 20230.00259
24 Aug 20230.00302
7 Sep 20230.00329
21 Sep 20230.00306
6 Oct 20230.00378
18 Oct 20230.01186
3 Nov 20230.00850
15 Nov 20230.02740
30 Nov 20230.27533
14 Dec 20230.02309
27 Dec 20230.38247
10 Jan 20240.02876
23 Jan 20240.03022
6 Feb 20240.09553
18 Feb 20240.03069
3 Mar 20240.05463
16 Mar 20240.03523
29 Mar 20240.06784
12 Apr 20240.15220
24 Apr 20240.04080
9 May 20240.06613
22 May 20240.05507
5 Jun 20240.04062
19 Jun 20240.10568
2 Jul 20240.04452
17 Jul 20240.10351
31 Jul 20240.06521
16 Aug 20240.27661
30 Aug 20240.10070
14 Sep 20240.15411
30 Sep 20240.07927
15 Oct 20240.13299
30 Oct 20240.01331
16 Nov 20240.01174
2 Dec 20240.01182
17 Dec 20240.01664
3 Jan 20250.02010
21 Jan 20250.01880
8 Feb 20250.01674
25 Feb 20250.01664
17 Mar 20250.00527
19 Mar 20250.00524
25 Mar 20250.00914
29 Mar 20250.02965
30 Mar 20250.00914
5 May 20250.00732
25 Jul 20250.00693
5 Dec 20250.01129
13 Apr 20260.03079
4 Jun 20260.03807
15 Jun 20260.02151
11 Aug 20260.02332

66 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 0.02332Published2021-07-14Index as of2026-08-11

The record had been public for 5 years when this index was last written.

Published 2021-07-14 receipt · Index as of 2026-08-11 derived

Siblings and hubs

Records related to this one

Its defect family

microsoft excel

Of the 21 records in this family, this is the only one holding a stated fix version: 15.0.5363.1000; 16.0.5188.100.

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

Family membership: computed, pro@dim2000

This record is one of a group, and the group's page describes all of them. This page is kept and dated, and the defect family's own page is the one we offer for indexing: the whole group.

Browse the index from here

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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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