CVE-2021-35642Network attack vector

High-privilege remote DoS via optimizer flaw

Published Oct 20, 2021 · Updated Sep 25, 2024

MySQL Server 8.0.26 and earlier contain an Optimizer flaw that allows remote authenticated users to cause a service interrupt via the MySQL protocol. The specific optimizer operation on attacker-controlled input is undisclosed in Oracle and NVD records. Exploitation requires high privileges and network access, and reported impact is a hang or repeatable crash without confidentiality or integrity loss.

CVSS severity4.9
Medium
EPSS probability2.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

MySQL Server 8.0.26 and earlier contain an Optimizer flaw that allows remote authenticated users to cause a service interrupt via the MySQL protocol. The specific optimizer operation on attacker-controlled input is undisclosed in Oracle and NVD records. Exploitation requires high privileges and network access, and reported impact is a hang or repeatable crash without confidentiality or integrity loss.

The record

CVE
CVE-2021-35642
Published
Oct 20, 2021
Updated
Sep 25, 2024
Vendor
Oracle Corporation
Product
MySQL Server
Classifications
Unavailable
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

4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P
4.9OracleCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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