LiveActive security incident?Get immediate response
CVE Record

CVE-2026-21968: 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 8.0.0-8.0.44, 8.4.0-8.4.7 and 9.0.0-9.5.0. Easily exploitable 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 6.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

MediumCVSS 6.5Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-21968 is a MySQL Server denial-of-service flaw. A low-privileged user with network access can trigger a hang or repeatable crash, making the database unavailable. The issue affects supported MySQL 8.0.0-8.0.44, 8.4.0-8.4.7, and 9.0.0-9.5.0 versions.

Executive priority

Treat as a near-term availability risk for business-critical MySQL services. Prioritize internet-reachable, shared, or high-dependency databases first. The main concern is outage and service disruption, not data theft, based on the provided sources.

Technical view

Oracle describes this as an easily exploitable vulnerability in MySQL Server’s Optimizer component. The CVSS 3.1 vector is AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, score 6.5. Impact is limited to availability; the supplied sources do not indicate confidentiality or integrity compromise.

Likely exposure

Exposure is most relevant where affected MySQL Server versions accept network connections from users or applications with database credentials. Internet exposure increases operational risk, but any reachable low-privileged account may be sufficient according to Oracle’s description.

Exploitation context

No active exploitation is stated in the provided sources, and this CVE is not marked as CISA KEV. The reported attack requirement is low privilege with network access via multiple protocols, with the outcome being a hang or complete denial of service.

Researcher notes

The public details identify the component as Server: Optimizer but do not provide root-cause specifics, exploit primitives, or fixed build numbers in the supplied bundle. Avoid assuming exploit availability or broader impact beyond denial of service until Oracle or CVE sources publish more detail.

Mitigation direction

  • Identify MySQL Server instances running affected supported version ranges.
  • Review Oracle’s January 2026 CPU advisory for official remediation guidance.
  • Apply vendor-supported updates or fixes when available for your release line.
  • Restrict MySQL network access to trusted application and administration paths.
  • Reduce unnecessary low-privileged accounts and rotate unused credentials.

Validation and detection

  • Inventory MySQL Server versions across production and non-production systems.
  • Confirm whether instances fall within the affected version ranges.
  • Review firewall and access-control paths to each MySQL service.
  • Check logs and monitoring for unexplained MySQL hangs or repeatable crashes.
  • Verify applied Oracle CPU guidance through change records and version checks.
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

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-2026-21968 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
6.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/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
6.5CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H2.83.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

6.5Medium
CVSS 3.1 vector shape for CVE-2026-21968Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/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 Server8.0.0, 8.4.0, 9.0.0Listed
Weakness

CWE details

No CWE listed

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