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Full vulnerability report · 2021
CVE-2021-29262High confidence

Misapplied Zookeeper ACLs can result in leakage of configured authentication and authorization settings

Apache Software Foundation · Apache Solr

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 6.72% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Apache Software Foundation Apache Solr and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

4 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcelucene-solrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcelucene-solrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcelucene-solrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcelucene-solrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-1115

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
01

What, why and how

When starting Apache Solr versions prior to 8.8.2, configured with the SaslZkACLProvider or VMParamsAllAndReadonlyDigestZkACLProvider and no existing security.json znode, if the optional read-only user is configured then Solr would not treat that node as a sensitive path and would allow it to be readable. Additionally, with any ZkACLProvider, if the security.json is already present, Solr will not automatically update the ACLs.

What

When starting Apache Solr versions prior to 8.8.2, configured with the SaslZkACLProvider or VMParamsAllAndReadonlyDigestZkACLProvider and no existing security.json znode, if the optional read-only user is configured then Solr would not treat that node as a sensitive path and would allow it to be readable. Additionally, with any ZkACLProvider, if the security.json is already present, Solr will not automatically update the ACLs.

Why

The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

When starting Apache Solr versions prior to 8.8.2, configured with the SaslZkACLProvider or VMParamsAllAndReadonlyDigestZkACLProvider and no existing security.json znode, if the optional read-only user is configured then Solr would not treat that node as a sensitive path and would allow it to be readable. Additionally, with any ZkACLProvider, if the security.json is already present, Solr will not automatically update the ACLs.

Why

The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Insufficiently Protected Credentials → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-522 ↗

CWE-522: Insufficiently Protected Credentials. The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-522
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

Cyber Security Agency of Singapore · English · CSA-SB-20210414Security Bulletin 14 Apr 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 14 Apr 2021, published on 14 April 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0556Multiples vulnérabilités dans les produits VMware

Record?id=CVE-2020-9546 Référence CVE CVE-2020-9547 https://www.cve.org/CVERecord?id=CVE-2020-9547 Référence CVE CVE-2020-9548 https://www.cve.org/CVERecord?id=CVE-2020-9548 Référence CVE CVE-2021-20190 https://www.cve.org/CVERecord?id=CVE-2021-20190 Référence CVE CVE-2021-22569 https://www.cve.org/CVERecord?id=CVE-2021-22569 Référence CVE CVE-2021-22573 https://www.cve.org/CVERecord?id=CVE-2021-22573 Référence CVE CVE-2021-23926 https://www.cve.org/CVERecord?id=CVE-2021-23926 Référence CVE CVE-2021-27807 https://www.cve.org/CVERecord?id=CVE-2021-27807 Référence CVE CVE-2021-27906 https://www.cve.org/CVERecord?id=CVE-2021-27906 Référence CVE CVE-2021-29262 https://www.cve.org/CVERecord?id=CVE-2021-29262 Référence CVE CVE-2021-29425 https://www.cve.org/CVERecord?id=CVE-2021-29425 Référence CVE CVE-2021-31811 https://www.cve.org/CVERecord?id=CVE-2021-31811 Référence CVE CVE-2021-31812 https://www.cve.org/CVERecord?id=CVE-2021-31812 Référence CVE CVE-2021-35515 https://www.cve.org/CVERecord?id=CVE-2021-35515 Référence CVE CVE-2021-35516 https://www.cve.org/CVERecord?id=CVE-2021-35516 Référence CVE CVE-2021-35517 https://www.cve.org/CVERecord?id=CVE-2021-35517 Référence CVE CVE-2021-36090 https://www.cve.org/CVERecord?id=CVE-2021-36090 Référence CVE CVE-2021-36373 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-005387Apache Solr における認証情報の不十分な保護に関する脆弱性

Apache Solr には、認証情報の不十分な保護に関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix not verified
Affected
Apache Solr: Apache Solr < 8.8.2
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 13 Apr 2021 · Last source change 3 Aug 2024, 22:02 UTC · CWE-522 · Insufficiently Protected Credentials

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-1115
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2021-1115↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-29262 · cve.blacktree.nl