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CVE Record

CVE-2026-21929: Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Parser).

Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Parser). Supported versions that are affected are 9.0.0-9.5.0. 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. CVSS 3.1 Base Score 5.3 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H).

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-21929 is a MySQL Server parser vulnerability that can let a low-privileged network user crash or hang the database. It affects availability, not data theft or modification, based on current sources. Exploitation is described as difficult, but a successful attack could disrupt applications that depend on affected MySQL versions.

Executive priority

Treat as a timely availability risk for business-critical MySQL environments. It does not currently indicate data compromise, but outages can affect revenue, operations, and service commitments. Prioritize patch planning or vendor-directed remediation for exposed and critical systems.

Technical view

Oracle reports an issue in MySQL Server, component Server: Parser, affecting supported versions 9.0.0 through 9.5.0. The CVSS 3.1 score is 5.3 with AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H. An attacker needs low privileges and network access through multiple protocols. Impact is complete denial of service via hang or repeatable crash.

Likely exposure

Organizations running Oracle MySQL Server 9.0.0 through 9.5.0 may be exposed, especially where authenticated database access is available over a network. Internet exposure is not required; internal users or compromised low-privilege accounts could be relevant.

Exploitation context

No provided source reports active exploitation, and the CVE is not marked in KEV. Oracle characterizes exploitation as difficult and requiring low privileges. The known impact is availability loss, not confidentiality or integrity compromise.

Researcher notes

The public description lacks CWE detail and does not include root-cause specifics beyond the parser component. Avoid assuming exploitability beyond Oracle’s CVSS vector. The source bundle has an affected-list inconsistency: structured data lists 9.0.0, while the description states 9.0.0-9.5.0.

Mitigation direction

  • Review Oracle’s January 2026 Critical Patch Update guidance for MySQL Server.
  • Identify MySQL Server instances running versions 9.0.0 through 9.5.0.
  • Prioritize systems supporting critical applications or shared production services.
  • Limit network access to MySQL services to required clients only.
  • Review low-privilege database accounts and remove unnecessary access.

Validation and detection

  • Inventory MySQL Server versions across production and non-production environments.
  • Confirm whether any instances run affected 9.0.0 through 9.5.0 versions.
  • Check Oracle advisory for applicable patched releases or vendor instructions.
  • Review database logs for unexplained crashes, hangs, or repeated restarts.
  • Verify network controls restrict database access to approved sources.
Prepared
Confidence
high
Sources
3

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-2026-21929 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
5.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:L/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
2Source 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
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H1.63.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2026-21929Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/PR:L/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 Server9.0.0Listed
Weakness

CWE details

No CWE listed

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