CVE-2021-29262Network attack vector

Authentication data disclosure via misapplied ZooKeeper ACLs

Published Apr 13, 2021 · Updated Aug 3, 2024

Information disclosure in Apache Solr before 8.8.2 allows remote attackers to read authentication data through ZooKeeper. Solr omits special ACL treatment for /security.json when a configured read-only user creates the znode, and it leaves existing ACLs unchanged at startup. Exposure requires a configured ZkACLProvider and either the optional read-only user on first creation or a pre-existing security.json znode, allowing ZooKeeper readers to obtain stored authentication and authorization settings.

CVSS severity7.5
High
EPSS probability6.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Apache Solr before 8.8.2 allows remote attackers to read authentication data through ZooKeeper. Solr omits special ACL treatment for /security.json when a configured read-only user creates the znode, and it leaves existing ACLs unchanged at startup. Exposure requires a configured ZkACLProvider and either the optional read-only user on first creation or a pre-existing security.json znode, allowing ZooKeeper readers to obtain stored authentication and authorization settings.

The record

CVE
CVE-2021-29262
Published
Apr 13, 2021
Updated
Aug 3, 2024
Vendor
The Apache Software Foundation
Product
Apache Solr
Classifications
CWE-522, T1552
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Apache Solr <8.8.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Solrversion=Apache Solr <8.8.2

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-522Insufficiently Protected Credentials
T1552Unsecured Credentials

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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