CVE-2021-2166Network attack vector

Authenticated denial of service via DML processing

Published Apr 22, 2021 · Updated Sep 26, 2024

Denial of service in Oracle MySQL MySQL Server 5.7.33 and earlier and 8.0.23 and earlier allows remote authenticated users to crash the server via the MySQL protocol. The affected DML processing operation is not disclosed in Oracle or MITRE records, so the exact untrusted input and code locus cannot be named. High-privileged network access is required, and successful requests can hang the server or cause repeatable crashes without confidentiality or integrity impact.

CVSS severity4.9
Medium
EPSS probability4.64%
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 MySQL Server 5.7.33 and earlier and 8.0.23 and earlier allows remote authenticated users to crash the server via the MySQL protocol. The affected DML processing operation is not disclosed in Oracle or MITRE records, so the exact untrusted input and code locus cannot be named. High-privileged network access is required, and successful requests can hang the server or cause repeatable crashes without confidentiality or integrity impact.

The record

CVE
CVE-2021-2166
Published
Apr 22, 2021
Updated
Sep 26, 2024
Vendor
Oracle Corporation
Product
MySQL Server
Classifications
Unavailable
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Apr 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 26, 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=5.7.33 and prior
  2. Affected versionversion=8.0.23 and prior

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Oracle Corporation · MySQL Serverversion=5.7.33 and prior; version=8.0.23 and prior

Published CVSS scores

4.0National Vulnerability DatabaseAV:N/AC:L/Au:S/C:N/I:N/A:P
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.

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

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

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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