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CVE-2021-44548

INDEX BUILT · 2026-09-20

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Apache Solr information disclosure vulnerability through DataImportHandler

CVE-2021-445484 of 4 sources documented this
29

rank 29 = 1 + 25 + 1 + 2 + 0

rank@v1 · scheduled

Someone is already using it

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

EPSS 0.05069  ·  without this subject the record ranks 28

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 4

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

rose on 2025-08-19  ·  without this subject the record ranks 28

How much of the world it touches

NVD CPE configurations

1 product in the CPE ranges  ·  without this subject the record ranks 27

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 29

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$253,000over the next 30 days, if this record is yours
Movement-$1.52Mon 2022-02-04, the last material move, 4 years, 5 months before this reading
Basisassumeda published average, not your estate

$253,000 = $4.99M incident cost x 1 exposure x 0.05069 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

0.05069EPSSNOT IN KEVas of 2026-09-20
Severity9.8 CRITICALreceipt
Harmtotal loss · unauthenticatedreceipt
Exploitationnone in held sources
Defensefix version namedreceipt
Movementdoubled within 72hreceipt
PLATEAU10Minimal movement since 2022-02-04, 1639 days at 0.05, as of 2026-08-01. 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 Apache Solr? 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-40 Path Traversal: '\\UNC\share\name\' (Windows UNC Share); CWE-20 Improper Input Validationreceipt
Published consequencesCWE-40: Confidentiality, Integrity: Read Files or Directories, Modify Files or Directories[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

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

Fixed in8.11.1receipt
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: 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, NVD9.8 CRITICALreceipt
Exploit probability0.05069 · top 8% of all CVEsreceipt
Blast breadth1 product across 1 vendorderived
Assigned byapachereceipt
Recorded changes29 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productApache Software Foundation Apache Solrreceipt
Published rangesapache solr < 8.11.1receipt
Fixed in8.11.1receipt

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 Improper Input Validation vulnerability in DataImportHandler of Apache Solr allows an attacker to provide a Windows UNC path resulting in an SMB network call being made from the Solr host to another host on the network. If the attacker has wider access to the network, this may lead to SMB attacks, which may result in: * The exfiltration of sensitive data such as OS user hashes (NTLM/LM hashes), * In case of misconfigured systems, SMB Relay Attacks which can lead to user impersonation on SMB Shares or, in a worse-case scenario, Remote Code Execution This issue affects all Apache Solr versions prior to 8.11.1. This issue only affects Windows. 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-20; CWE-40; CWE-22
affected versions
apache solr < 8.11.1

check it yourself solr.apache.org security.netapp.com receipt

Dated events

2022-01-08EPSS moved 0.01 to 0.242022-02-04EPSS moved 0.32 to 0.022025-08-19EPSS moved 0.01 to 0.06

Movement the material steps

24 Dec 20210.00918
8 Jan 20220.2416 · crossed 0.10
4 Feb 20220.01978 · crossed 0.10
7 Mar 20230.00206 · scoring model v2023.03.01
17 Mar 20250.0227 · scoring model v2025.03.14
15 Jun 20260.05087 · scoring model v2026.06.15
1 Aug 20260.05069

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

Show all 29 observations
24 Dec 20210.00918
8 Jan 20220.2416
14 Jan 20220.32399
4 Feb 20220.01978
7 Mar 20230.00206
9 May 20230.00209
5 Jun 20230.00293
16 Jul 20230.00349
31 Jul 20230.00364
8 Dec 20230.00459
20 Dec 20230.00412
16 Mar 20240.00486
29 Jul 20240.00528
7 Sep 20240.00631
17 Dec 20240.00298
23 Feb 20250.00358
17 Mar 20250.0227
19 Mar 20250.02132
29 Mar 20250.0545
30 Mar 20250.02132
14 Apr 20250.01129
18 Aug 20250.01123
19 Aug 20250.06377
5 Sep 20250.05762
21 Nov 20250.05017
11 Dec 20250.0666
29 Apr 20260.05017
15 Jun 20260.05087
1 Aug 20260.05069

29 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 0.05069Published2021-12-23Index as of2026-08-01

Exploit probability more than doubled between 2025-08-18 and 2025-08-19 (0.01123 → 0.06377) and the record had been public for 4 years, 7 months when this index was last written.

Published 2021-12-23 receipt · Index as of 2026-08-01 derived

Siblings and hubs

Records related to this one

Its defect family

apache software foundation apache solr

Of the 2 records in this family, this is the only one that does not hold public proof-of-concept code. That is a fact about what the catalogue records, not a finding about exposure.

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

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