Security readout for executives and security teams
Plain-English summary
CVE-2026-21941 is a denial-of-service issue in Oracle MySQL Server. A highly privileged user with network access could cause MySQL Server to hang or crash repeatedly. It does not indicate data theft or data modification, but it can disrupt applications that depend on affected MySQL databases.
Executive priority
Treat as a resilience and uptime risk, not a confidentiality breach based on current sources. Prioritize remediation for business-critical databases, externally reachable services, and environments with many privileged database users.
Technical view
Oracle describes the flaw in MySQL Server’s Optimizer component, classified as CWE-400. Affected supported versions are 8.0.0-8.0.44, 8.4.0-8.4.7, and 9.0.0-9.5.0. CVSS is 4.9: network exploitable, low complexity, high privileges required, no user interaction, availability impact only.
Likely exposure
Exposure is mainly MySQL Server instances running affected versions where highly privileged database users can connect over the network. Internet exposure increases operational risk, but exploitation still requires high privileges according to Oracle.
Exploitation context
No active exploitation is indicated in the provided sources, and the CVE is not listed as KEV. Oracle states the issue is easily exploitable by a high-privileged attacker with network access via multiple protocols.
Researcher notes
Public details are limited to Oracle and CVE metadata. The affected component is Optimizer, but no root-cause details or safe reproduction method are provided. Avoid assuming broader impact beyond complete denial of service against affected MySQL Server versions.
Mitigation direction
- Review Oracle’s January 2026 Critical Patch Update guidance for MySQL Server.
- Prioritize updating affected MySQL Server versions in production and internet-reachable environments.
- Restrict network access to MySQL services to trusted systems and administrators.
- Audit and minimize high-privileged MySQL accounts.
- Monitor MySQL availability and repeated crash or hang events.
Validation and detection
- Inventory MySQL Server versions across all environments.
- Identify instances running 8.0.0-8.0.44, 8.4.0-8.4.7, or 9.0.0-9.5.0.
- Confirm which users have high privileges and network access.
- Check whether Oracle CPU updates have been applied.
- Review logs for unexplained hangs, restarts, or repeated crashes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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.
CWE-400: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-21941 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- 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
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.
CVSS vector scores
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H1.23.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.9MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- Oracle AdvisoryCVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.