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CVE Record

CVE-2021-35634: 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-2021-35634 is a MySQL Server availability flaw. A highly privileged user who can connect to MySQL over the network may be able to make the server hang or crash repeatedly. This is primarily an outage risk, not a data theft or data modification issue based on the provided CVSS vector.

Executive priority

Prioritize remediation for production MySQL systems where downtime has business impact or privileged access is broadly distributed. This is a medium-severity availability issue; it should not displace critical remote-code-execution or data-exposure fixes unless the affected database supports important services.

Technical view

Oracle describes the issue in MySQL Server Optimizer affecting supported versions 8.0.26 and prior. The CVSS vector is AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H, meaning network reachable, low complexity, high privileges required, no user interaction, and high availability impact only.

Likely exposure

Exposure is most likely where Oracle MySQL Server 8.0.26 or earlier is running and reachable by highly privileged database users over supported network protocols. Risk is lower where administrative database access is tightly restricted, monitored, and isolated from untrusted networks.

Exploitation context

The source bundle says the vulnerability is easily exploitable, but only by a high-privileged attacker. It is not listed as CISA KEV, and the provided sources do not state active exploitation. Treat suspicious repeated MySQL crashes as operational signals, not proof of exploitation.

Researcher notes

The available evidence supports a denial-of-service impact in MySQL Server Optimizer only. No CWE, exploit details, or active exploitation evidence are provided. Avoid expanding scope beyond Oracle MySQL Server 8.0.26 and prior, and use vendor advisories for fixed-version confirmation.

Mitigation direction

  • Apply Oracle's October 2021 CPU guidance or a later vendor-supported fixed MySQL release.
  • Confirm MySQL Server is no longer version 8.0.26 or earlier where this CVE applies.
  • Restrict privileged MySQL access to trusted administrators and management networks.
  • Review NetApp advisory NTAP-20211022-0003 if NetApp products are in scope.
  • Monitor MySQL availability and crash patterns until remediation is complete.

Validation and detection

  • Inventory MySQL Server instances and record exact versions.
  • Identify hosts running MySQL Server 8.0.26 or earlier.
  • Review who has high-privileged MySQL accounts and network reachability.
  • Check MySQL error logs for unexplained hangs or repeated crashes.
  • Verify vendor advisory applicability for Oracle and NetApp-managed environments.
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

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CVE-2021-35634 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-2021-35634Attack 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.