LiveActive security incident?Get immediate response
CVE Record

CVE-2021-35644: 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
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-35644 can let an already high-privileged network user crash or hang MySQL Server. This is mainly an availability risk: outages, failed transactions, and operational disruption, not data theft or privilege escalation based on the provided sources.

Executive priority

Treat as a scheduled but important database availability fix. Prioritize internet-exposed, mission-critical, or multi-tenant MySQL environments first, especially where many users or services have privileged database access.

Technical view

Oracle describes a MySQL Server Optimizer vulnerability 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, and high availability impact.

Likely exposure

Exposure is most likely where MySQL Server 8.0.26 or earlier accepts network connections from privileged database users. Publicly reachable administration paths, shared DBA accounts, or weak privilege separation increase business risk.

Exploitation context

The provided bundle does not show active exploitation, public exploit use, or KEV listing. Successful abuse requires high privileges, but could still cause a repeatable denial of service against production MySQL workloads.

Researcher notes

Evidence supports denial of service only. The vulnerability is in MySQL Server Optimizer and needs high privileges over network-accessible protocols. The bundle does not provide exploit details, proof-of-concept status, or a named fixed version.

Mitigation direction

  • Apply Oracle's October 2021 Critical Patch Update guidance for MySQL Server.
  • Upgrade affected MySQL Server 8.0.26 or earlier deployments per vendor guidance.
  • Restrict MySQL network access to trusted administration and application sources.
  • Review and reduce high-privileged database accounts where possible.
  • Check NetApp advisory applicability for embedded or packaged MySQL exposure.

Validation and detection

  • Inventory MySQL Server versions and flag 8.0.26 or earlier.
  • Confirm Oracle CPU October 2021 or later security fixes are applied.
  • Review MySQL network exposure across production and management networks.
  • Audit privileged MySQL accounts and recent administrative access.
  • Check monitoring for unexplained MySQL hangs, crashes, or restarts.
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.

cve · low confidence lookup

CVE-2021-35644 mapping review

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

Open ATT&CK lookup
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-2021-35644Attack 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.