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Response snapshot Nov 4, 2026, 13:46 UTC

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VulnerabilityCVE-2026-100302

Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a...

Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a single small request.

At a glance

Exploited
Not known
Severity
7.1 High (CVSS 4.0)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-100302 (opens a new tab)

What happened

Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a single small request.

The multiRead handler places no limit on the number of bundled read operations or on the cumulative size of the response it builds in memory. Because each operation's result is fully materialized and retained before serialization, a request that is small on the wire — within the jute.

maxbuffer limit — but that references a large znode many times can force the server to allocate far more heap than the request size implies, exhausting the JVM heap and terminating the server with an OutOfMemoryError. Neither jute.maxbuffer nor largeRequestMaxBytes prevents this, as both bound only the inbound request, not the response.

This issue affects Apache ZooKeeper from 3.7.0 through 3.9.6. Users are recommended to upgrade to version 3.9.7, which enforces configurable limits on the multiRead operation count and cumulative response size.

Scores and how they were measured

CVSS base severity

7.1

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Sources

  1. Primary source

    NVD CVE-2026-100302 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  6. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, November 4). Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a... (CVE-2026-100302). https://kevwire.com/record/CVE-2026-100302

MLA

"Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a... (CVE-2026-100302)." KEVWire, 4 Nov. 2026, kevwire.com/record/CVE-2026-100302.

Chicago

KEVWire. "Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a... (CVE-2026-100302)." Last modified November 4, 2026. https://kevwire.com/record/CVE-2026-100302.

Evidence summary (plain text)

Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a... (Nov 4, 2026).
Allocation of Resources Without Limits or Throttling in the multiRead request handler of Apache ZooKeeper allows a remote attacker to crash the server (denial of service) with a single small request.

The multiRead handler places no limit on the number of bundled read operations or on the cumulative size of the response it builds in memory.
CVSS 7.1 (version 4.0; evidence as of Nov 4, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-100302).
Sources:
NVD CVE-2026-100302: https://nvd.nist.gov/vuln/detail/CVE-2026-100302
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-04T12:11:01.101Z&lastModEndDate=2026-11-04T13:45:56.267Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-04T11:40:57.013Z&lastModEndDate=2026-11-04T13:10:58.202Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-04T11:06:02.059Z&lastModEndDate=2026-11-04T12:40:56.314Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-04T10:30:59.408Z&lastModEndDate=2026-11-04T12:05:58.403Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-04T10:01:02.069Z&lastModEndDate=2026-11-04T11:30:56.477Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-100302.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Nov 4, 2026, 13:45 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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