CVE-2021-2356Network attack vector

Authenticated data alteration and server crash

Published Jul 20, 2021 · Updated Sep 26, 2024

Replication flaw in Oracle MySQL Server 5.7.34 and earlier and 8.0.25 and earlier allows remote authenticated users to alter data or crash the server. Oracle identifies Server: Replication as the locus but has not published the flawed operation or the input that triggers it. Exploitation requires low-privileged MySQL access, high attack complexity, and network reachability; successful attacks can update, insert, or delete some accessible data, hang the service, or cause repeatable crashes.

CVSS severity5.9
Medium
EPSS probability2.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Replication flaw in Oracle MySQL Server 5.7.34 and earlier and 8.0.25 and earlier allows remote authenticated users to alter data or crash the server. Oracle identifies Server: Replication as the locus but has not published the flawed operation or the input that triggers it. Exploitation requires low-privileged MySQL access, high attack complexity, and network reachability; successful attacks can update, insert, or delete some accessible data, hang the service, or cause repeatable crashes.

The record

CVE
CVE-2021-2356
Published
Jul 20, 2021
Updated
Sep 26, 2024
Vendor
Oracle Corporation
Product
MySQL Server
Classifications
T1565.001, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 20, 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=5.7.34 and prior
  2. Affected versionversion=8.0.25 and prior

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Oracle Corporation · MySQL Serverversion=5.7.34 and prior; version=8.0.25 and prior

Published CVSS scores

4.9NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:P
5.9Oracle CorporationCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1565.001Stored Data Manipulation
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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