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CVE Record

CVE-2021-35646: 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 8.0.26 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-2021-35646 is a denial-of-service flaw in Oracle MySQL Server’s Optimizer component. A highly privileged attacker who can reach MySQL over the network may make the server hang or crash repeatedly. It affects MySQL Server 8.0.26 and prior. The business impact is service availability, not data theft or tampering based on the provided sources.

Executive priority

Prioritize remediation for business-critical MySQL systems where outage would disrupt operations. This is not presented as a data breach issue in the sources, but repeated database crashes can still create material downtime risk.

Technical view

The CVSS 3.1 vector is AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H, score 4.9. Exploitation requires high privileges and network access via multiple protocols. Successful exploitation can cause complete denial of service through hangs or frequently repeatable crashes. The source bundle does not provide CWE mapping, exploit details, or fixed-version specifics.

Likely exposure

Exposure is most likely where MySQL Server 8.0.26 or earlier remains deployed and highly privileged database accounts can connect over the network. Internet exposure is not required; internal privileged access is enough under the CVSS vector.

Exploitation context

The CVE is not listed as KEV in the provided bundle, and no source in the bundle states active exploitation. The required high privileges reduce likelihood, but the low attack complexity and complete availability impact make it relevant for critical databases.

Researcher notes

Evidence supports a network-reachable, high-privilege denial-of-service issue in MySQL Server Optimizer. The provided bundle does not include root cause detail, proof-of-concept status, CWE classification, or named fixed versions. Avoid assuming exploit availability or broader product impact beyond listed sources.

Mitigation direction

  • Inventory MySQL Server instances and identify versions 8.0.26 or prior.
  • Review Oracle October 2021 CPU guidance and apply vendor-recommended MySQL updates.
  • Check NetApp guidance if MySQL is bundled with affected NetApp products.
  • Restrict network paths to MySQL management and database interfaces.
  • Review highly privileged MySQL accounts and remove unnecessary access.

Validation and detection

  • Confirm MySQL Server versions across production, staging, and managed images.
  • Verify applicable Oracle CPU remediation is installed per vendor guidance.
  • Check whether NetApp advisory scope applies to deployed products.
  • Review database logs for unexplained crashes or repeated service hangs.
  • Validate privileged account access paths are limited and documented.
Prepared
Confidence
high
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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

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CVE-2021-35646 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-2021-35646Attack 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 Server8.0.26 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.