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CVE Record

CVE-2021-2356: Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Replication).

Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Replication). Supported versions that are affected are 5.7.34 and prior and 8.0.25 and prior. Difficult to exploit vulnerability allows low privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server as well as unauthorized update, insert or delete access to some of MySQL Server accessible data. CVSS 3.1 Base Score 5.9 (Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H).

MediumCVSS 5.9Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This MySQL Server replication vulnerability can let a low-privileged network user disrupt the database or make unauthorized changes to some accessible data. It is rated medium because exploitation is difficult, but the business impact can still be meaningful for systems where MySQL availability or data integrity is critical.

Executive priority

Treat as a scheduled but real remediation item. Prioritize production MySQL servers supporting critical applications, exposed network paths, or broad low-privileged account access.

Technical view

CVE-2021-2356 affects Oracle MySQL Server 5.7.34 and prior and 8.0.25 and prior, in the Server: Replication component. CVSS 3.1 is 5.9, with network attack vector, high complexity, low privileges required, no user interaction, low integrity impact, and high availability impact.

Likely exposure

Exposure is most likely where affected MySQL Server versions are reachable over the network by low-privileged authenticated users or service accounts, especially environments using replication features.

Exploitation context

The source bundle does not show active exploitation, and CISA KEV status is false. Oracle describes exploitation as difficult and requiring low privileges plus network access via multiple protocols.

Researcher notes

No CWE is listed in the supplied CVE data. Public details identify the replication component and impacts, but not enough root-cause detail to validate by behavior without vendor patches or controlled regression testing.

Mitigation direction

  • Identify MySQL Server instances at 5.7.34 and prior or 8.0.25 and prior.
  • Apply Oracle, operating system, appliance, or platform vendor updates for affected MySQL Server deployments.
  • Restrict MySQL network access to trusted hosts and required application paths.
  • Review low-privileged database accounts and remove unnecessary replication or broad data permissions.
  • Check NetApp or Fedora advisories if MySQL is supplied through those ecosystems.

Validation and detection

  • Inventory MySQL Server versions and confirm whether they fall within the affected ranges.
  • Verify vendor security updates are installed through package or platform management records.
  • Confirm MySQL listener exposure is limited to approved networks and applications.
  • Review database account privileges for unnecessary access to replication or modifiable data.
  • Monitor MySQL crash, hang, and unexpected data modification signals after remediation.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-2356 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.9 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.9CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H1.64.2Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.9Medium
CVSS 3.1 vector shape for CVE-2021-2356Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Oracle CorporationMySQL Server5.7.34 and prior, 8.0.25 and priorListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.