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CVE Record

CVE-2021-2426: Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer).

Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer). Supported versions that are affected are 8.0.25 and prior. Easily exploitable vulnerability allows high 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. CVSS 3.1 Base Score 4.9 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

MediumCVSS 4.9Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-2426 can let a highly privileged MySQL user remotely make the server hang or crash repeatedly. It is availability-only, but downtime in a production database can interrupt customer-facing services, internal applications, and operational workflows.

Executive priority

Treat as a scheduled but real availability risk. Prioritize internet-facing, business-critical, or shared MySQL environments first, especially where privileged account control is weak or operational downtime is costly.

Technical view

Oracle describes this as a MySQL Server Optimizer vulnerability affecting supported MySQL Server 8.0.25 and prior. Attack prerequisites are network access over multiple protocols and high privileges. Successful exploitation can cause a complete denial of service through hangs or repeatable crashes. CVSS 3.1 score is 4.9.

Likely exposure

Exposure is most likely where MySQL Server 8.0.25 or earlier remains deployed and high-privileged database accounts can connect over the network. Internet exposure increases operational risk, but the privilege requirement limits broad opportunistic exploitation.

Exploitation context

The provided sources do not indicate active exploitation, and this CVE is not listed as KEV in the source bundle. The main concern is misuse by an authenticated, highly privileged user or compromised privileged account to disrupt database availability.

Researcher notes

The source bundle identifies impact and prerequisites but does not include root cause details, proof-of-concept status, or exact fixed version mapping. Validation should focus on version inventory, privilege exposure, and vendor advisory alignment rather than exploit reproduction.

Mitigation direction

  • Identify all MySQL Server instances running 8.0.25 or earlier.
  • Apply Oracle CPU guidance or upgrade beyond affected versions per vendor documentation.
  • Restrict network access to MySQL from trusted application and administration hosts.
  • Review and reduce high-privileged MySQL accounts where operationally possible.
  • Check NetApp advisory guidance if MySQL is embedded in managed products.

Validation and detection

  • Confirm MySQL Server versions across production, staging, and backup environments.
  • Verify no affected MySQL versions remain after patching or upgrade.
  • Review database account privileges for unnecessary high-privileged access.
  • Check firewall rules and security groups limiting MySQL network reachability.
  • Monitor database logs for unexpected crashes, hangs, or restart patterns.
Prepared
Confidence
medium
Sources
4

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-2021-2426 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
4.9 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/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
3Source 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
4.9CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H1.23.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

4.9Medium
CVSS 3.1 vector shape for CVE-2021-2426Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/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 Server8.0.25 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.