CVE-2026-21964Network attack vector

Authenticated server hang or repeatable crash

Published Jan 20, 2026 · Updated Jan 20, 2026

Denial of service in Oracle MySQL Server Thread Pooling allows remote authenticated users to hang or repeatedly crash affected servers. Oracle identifies the Thread Pooling component but has not disclosed the faulty operation or the input that triggers it. Affected releases are 8.0.0 through 8.0.44, 8.4.0 through 8.4.7, and 9.0.0 through 9.5.0; exploitation requires high-privilege network access and affects availability only.

CVSS severity4.9
Medium
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Oracle MySQL Server Thread Pooling allows remote authenticated users to hang or repeatedly crash affected servers. Oracle identifies the Thread Pooling component but has not disclosed the faulty operation or the input that triggers it. Affected releases are 8.0.0 through 8.0.44, 8.4.0 through 8.4.7, and 9.0.0 through 9.5.0; exploitation requires high-privilege network access and affects availability only.

The record

CVE
CVE-2026-21964
Published
Jan 20, 2026
Updated
Jan 20, 2026
Vendor
Oracle Corporation
Product
MySQL Server
Classifications
T1499
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jan 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 20, 2026Record 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=8.0.0 <=8.0.44
  2. Affected versionversion=8.4.0 <=8.4.7
  3. Affected versionversion=9.0.0 <=9.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Oracle Corporation · MySQL Serverversion=8.0.0 <=8.0.44; version=8.4.0 <=8.4.7; version=9.0.0 <=9.5.0

Published CVSS scores

4.9Oracle CorporationCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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