CVE-2021-35644Network attack vector

High-privilege service interruption

Published Oct 20, 2021 · Updated Sep 25, 2024

Denial of service in Oracle MySQL Server 8.0.26 and earlier allows remote authenticated users to cause a hang or repeatable crash. The flaw resides in the Server Optimizer, but Oracle has not disclosed the incorrect optimizer operation or triggering query. Exploitation requires network access over the MySQL protocol and a highly privileged account; impact is limited to service interruption.

CVSS severity4.9
Medium
EPSS probability1.94%
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 8.0.26 and earlier allows remote authenticated users to cause a hang or repeatable crash. The flaw resides in the Server Optimizer, but Oracle has not disclosed the incorrect optimizer operation or triggering query. Exploitation requires network access over the MySQL protocol and a highly privileged account; impact is limited to service interruption.

The record

CVE
CVE-2021-35644
Published
Oct 20, 2021
Updated
Sep 25, 2024
Vendor
Oracle Corporation
Product
MySQL Server
Classifications
T1499
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Oct 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 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=8.0.26 and prior

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Oracle Corporation · MySQL Serverversion=8.0.26 and prior

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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