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No exploitation reportedFix available

CVE-2021-44548

No exploitation reported by the sources we read.

  • Published2021-12-23
  • Fixed in8.11.1
  • WeaknessCWE-20 · CWE-22 · CWE-40

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2021-12-2309:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-44548?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-44548?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Apache solrversion to verify
BranchAffectedFixed in
8.11< 8.11.18.11.1

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Apache solr to 8.11.1

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVSS 3.19.8read 2026-10-23
  • NVDCVSS 2.06.8read 2026-10-23
  • CNAweakness (CWE)CWE-20, CWE-40read 2026-10-23
  • NVDweakness (CWE)CWE-22read 2026-10-23
  • FIRST EPSSEPSS score5.2 %2026-10-22
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2021-12-23
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2021-44548?

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.

Is CVE-2021-44548 actively exploited?

Active exploitation of CVE-2021-44548 has not been confirmed. Its EPSS score was 5.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-44548?

CVE-2021-44548 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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