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CVE-2021-40865

INDEX BUILT · 2026-09-20

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Unsafe Pre-Authentication Deserialization In Workers

CVE-2021-408654 of 4 sources documented this
55

rank 55 = 25 + 25 + 0 + 5 + 0

rank@v1 · this cycle

Someone is already using it

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

EPSS 0.65587  ·  without this subject the record ranks 30

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 30

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 55

How much of the world it touches

NVD CPE configurations

3 products in the CPE ranges  ·  without this subject the record ranks 50

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 55

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$3.27Mover the next 30 days, if this record is yours
Movement-$262,000on 2025-11-21, the last material move, 6 months before this reading
Basisassumeda published average, not your estate

$3.27M = $4.99M incident cost x 1 exposure x 0.65587 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

0.65587EPSSNOT IN KEVas of 2026-09-20
Severity9.8 CRITICALreceipt
Harmtotal loss · unauthenticatedreceipt
Exploitationpublic proof-of-conceptreceipt
Defenseunaffected versions publishedreceipt
Movementthreshold crossedreceipt
RISING10Risen from 0.01374 to 0.65587 across 33 observations. arc-rules@v1

Foresight · where to check next

CVE-2023-43208CVE-2022-31199CVE-2021-35464CVE-2021-42237SonicWall SMA1000SolarWinds Web40865

This record is one instance of CWE-502, deserialization of untrusted data. The index holds 3288 prior instances of this class, 76 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1

Full pattern panel

Prior records in this weakness class. Each is its own record, dated and receipted.
Color is a claim, not decoration:the hostile worldthe defenseno signalspoke length is how much of the record matches, not how bad it is

Running Apache Storm? 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.

Reachnetwork-reachable · no privileges required · no user interaction · low attack complexityreceipt
ImpactComplete confidentiality, integrity and availability lossreceipt
Scored fromCVSS v3.1 · NVD's vectorreceipt
Weakness classCWE-502 Deserialization of Untrusted Datareceipt
Published consequencesCWE-502: Integrity: Modify Application Data, Unexpected State; Availability: DoS: Resource Consumption (CPU); Other: Varies by Context[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 branchstorm 1.2.4; storm 2.1.1; storm 2.2.1receipt
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: Proof-of-concept published · 1 public repository, 2021-11-26.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published · 1 public repository2021-11-26receipt
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, NVD9.8 CRITICALreceipt
Exploit probability0.65587 · top 0.77% of all CVEsreceipt
Blast breadth1 product across 1 vendorderived
Assigned byapachereceipt
Recorded changes36 · last 18 Sep 2026derived

Affected & Fixed Versions as published

Affected productApache Software Foundation Apache Stormreceipt
Published rangesapache storm >= 1.0.0 < 1.2.4; apache storm >= 2.1.0 < 2.1.1; apache storm >= 2.2.0 < 2.2.1receipt

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 Unsafe Deserialization vulnerability exists in the worker services of the Apache Storm supervisor server allowing pre-auth Remote Code Execution (RCE). Apache Storm 2.2.x users should upgrade to version 2.2.1 or 2.3.0. Apache Storm 2.1.x users should upgrade to version 2.1.1. Apache Storm 1.x users should upgrade to version 1.2.4 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-502
affected versions
apache storm >= 1.0.0 < 1.2.4; apache storm >= 2.1.0 < 2.1.1; apache storm >= 2.2.0 < 2.2.1

check it yourself lists.apache.org seclists.org receipt

Dated events

2022-01-06EPSS moved 0.04 to 0.162025-03-17EPSS moved 0.01 to 0.702026-06-15EPSS moved 0.46 to 0.66

Movement the material steps

26 Oct 20210.01374
6 Jan 20220.15833 · crossed 0.10
1 Apr 20220.01978 · crossed 0.10
7 Mar 20230.03492 · scoring model v2023.03.01
17 Mar 20250.69981 · crossed 0.10 and 0.50 · scoring model v2025.03.14
22 Apr 20250.58834
8 Jul 20250.49399 · crossed 0.50
18 Nov 20250.51471 · crossed 0.50
21 Nov 20250.4622 · crossed 0.50
15 Jun 20260.65587 · crossed 0.50 · scoring model v2026.06.15

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

Show all 33 observations
26 Oct 20210.01374
29 Oct 20210.04024
6 Jan 20220.15833
4 Feb 20220.22009
1 Apr 20220.01978
7 Mar 20230.03492
11 Mar 20230.04679
18 May 20230.03964
2 Jun 20230.04123
14 Aug 20230.02952
10 Oct 20230.03083
19 Dec 20230.02198
17 Jan 20240.01919
31 May 20240.01477
10 Jul 20240.01248
17 Dec 20240.00520
26 Dec 20240.00737
14 Mar 20250.00535
17 Mar 20250.69981
19 Mar 20250.67743
20 Mar 20250.69981
27 Mar 20250.67743
28 Mar 20250.69981
29 Mar 20250.67743
30 Mar 20250.69981
16 Apr 20250.69487
22 Apr 20250.58834
4 May 20250.54681
8 Jul 20250.49399
23 Sep 20250.4622
18 Nov 20250.51471
21 Nov 20250.4622
15 Jun 20260.65587

33 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 0.65587Published2021-10-25Public PoC2021-11-26Index as of2026-06-15

Exploit probability more than doubled between 2021-10-26 and 2021-10-29 (0.01374 → 0.04024) and the record had been public for 4 years, 7 months when this index was last written.

Published 2021-10-25 receipt · Public PoC 2021-11-26 receipt · Index as of 2026-06-15 derived

The pattern, elsewhere

This record is one instance of CWE-502, deserialization of untrusted data. The index holds 3288 prior instances of this class, 76 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]

CVE-2023-43208matches 8 of 8KEV listed · 2023receipt
CVE-2022-31199matches 8 of 8KEV listed · 2022receipt
CVE-2021-35464matches 8 of 8KEV listed · 2021receipt
CVE-2021-42237matches 8 of 8KEV listed · 2021receipt
CVE-2025-23006 · SonicWall SMA1000matches 8 of 9KEV listed · 2025receipt
CVE-2025-26399 · SolarWinds Web Help Deskmatches 8 of 9KEV listed · 2025receipt

"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1

3288 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.

No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.

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