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MySQL Server EUVDEUVD-2026-106167

| CVE-2026-101766 MEDIUM
Improper Access Control (CWE-284)
2026-10-20 secalert_us@oracle.com GHSA-46hr-hq68-7v32
4.4
CVSS 3.1 · Vendor: oracle
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain high-privilege DB account
  2. Exploit
    Connect to Replication component over network
  3. Execution
    Trigger crash/hang condition
  4. Impact
    Complete denial of service

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK

1 technique across 1 tactic: Defense Evasion

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation targets the Server: Replication component and requires the attacker to already hold high MySQL privileges (PR:H) with network access over one of multiple supported protocols. Limiting factors are significant: the attacker must be authenticated as a high-privileged user before exploitation, and Oracle explicitly rates the flaw as 'difficult to exploit' (AC:H), implying specific timing, state, or configuration conditions must be met. No end-user interaction is needed (UI:N), and the only outcome is a hang or repeatable crash (complete DoS) - there is no data exposure or modification. Affected deployments are MySQL Server 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1 and MySQL Cluster 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1.

Impact

This is a genuinely low-priority issue despite its network attack vector. The CVSS 3.1 base score of 4.4 (MEDIUM) accurately reflects a constrained threat: the vector AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H shows that exploitation requires high privileges (PR:H) already on the target and has high attack complexity (AC:H), while the only impact is availability (A:H) - a hang or repeatable crash, with no confidentiality or integrity loss. No EPSS score was provided in the input, so exploitation probability cannot be quantified. The CVE is NOT listed in CISA KEV and no public exploit code is referenced, so there is no public exploit identified at time of analysis. The signals are consistent rather than conflicting: a high-complexity, high-privilege, availability-only flaw reported through Oracle's routine quarterly Critical Patch Update is the profile of a low real-world risk rather than an urgent priority. An attacker who already holds high MySQL privileges can generally cause disruption by other means, further reducing the marginal risk this adds.

Exploit ScenarioDerived

An attacker who has already obtained high-privilege database credentials connects to MySQL Server or Cluster over the network via one of multiple supported protocols and sends crafted input to the Replication component, triggering a server hang or a reliably repeatable crash (complete DoS). The high attack complexity means specific timing or conditions must be met, and no public proof-of-concept is known, so successful exploitation is non-trivial.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 21, 2026

A difficult-to-exploit denial-of-service flaw in Oracle MySQL's Server: Replication component lets a high-privileged, network-connected database user hang or repeatedly crash MySQL Server 8.4.0-8.4.12, 9.7.0-9.7.3 and 26.7.0-26.7.1, as well as MySQL Cluster 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3 and 26.7.0-26.7.1. Because the CVSS vector requires PR:H credentials and high attack complexity (AC:H), only authenticated administrators or accounts with replication-level privileges can trigger it, and no confidentiality or integrity impact results - availability only, at a base score of 4.4. No public exploit code or confirmed active exploitation was identified at time of analysis, and no EPSS score was supplied with the source data.

RemediationAI

Apply the Oracle Critical Patch Update referenced at https://www.oracle.com/security-alerts/cpuoct2026.html - the exact patched build numbers are not enumerated in the provided data, so confirm the fixed release for your branch (8.4.x, 9.7.x, 26.7.x, or the corresponding MySQL Cluster/NDB build) against the CPU before scheduling the upgrade; note that MySQL upgrades require a rolling restart and, for Cluster, a data-node rolling restart that temporarily reduces redundancy. Where immediate patching is not possible, the highest-value compensating control is privilege reduction: because exploitation requires PR:H, audit and revoke REPLICATION SLAVE, REPLICATION CLIENT, and equivalent NDB replication privileges from all but the minimal set of accounts, and enforce source-host restrictions so replication-capable accounts can only connect from known replica hosts - the trade-off is that legitimate replica provisioning and failover automation must be updated in lockstep or replication will break. Further tighten network exposure by binding replication listeners to a dedicated management VLAN or blocking port 3306/ndb ports at the perimeter, accepting that this only removes the AV:N path and does not fix the underlying defect. Finally, tune restart automation and monitoring on replication-heavy instances so that if a hang or crash-loop is triggered, alerting and automatic failover limit the outage window, recognizing that this is an availability mitigation only and leaves the vulnerable code in place.

Affected VersionsENISA

MySQL Cluster 8.4.0-8.4.12
MySQL Server 9.7.0-9.7.3
MySQL Cluster 9.7.0-9.7.3
MySQL Cluster 26.7.0-26.7.1
MySQL Server 8.4.0-8.4.12
MySQL Cluster 8.0.0-8.0.49
MySQL Server 26.7.0-26.7.1

Affected Packages

euvd mysql_cluster no fix
euvd mysql_server no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The flaw lives in the replication subsystem shared by MySQL Server and MySQL Cluster, the machinery responsible for binary log shipping, replica apply threads, and (in Cluster) the NDB replication channels that keep data nodes and SQL nodes synchronized. Oracle does not publish a CWE mapping for this CPU entry, so the root-cause class is best described functionally: malformed or mistimed replication traffic from a privileged session drives the server into a state it cannot recover from, producing a hang or a repeatable crash of the mysqld (or data node) process rather than memory corruption with code-execution potential. The CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H vector confirms the practical constraints - reachable over multiple supported protocols on the network, but gated behind high privileges and conditions Oracle itself calls "difficult to exploit," meaning specific timing, replication topology, or server-state preconditions must align. Only the availability impact is scored (A:H), with C:N/I:N, so the worst realistic outcome is an outage or restart loop, not data disclosure or tampering. Both the 8.0.x/8.4.x LTS lines and the newer 9.7.x and 26.7.x innovation lines are in scope, which indicates the defect predates the most recent branch and was carried forward through the replication code refactors.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (oracle) PRIMARY 4.4 MEDIUM
AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
vuln.today AI 4.4 MEDIUM

Network-reachable but requires pre-existing high DB privileges (PR:H) and difficult conditions (AC:H); impact is availability-only crash/hang, so C:N/I:N/A:H.

3.1 AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:H/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Red Hat 4.4 MEDIUM

Primary rating from Vendor (oracle).

CVSS VectorVendor: oracle

Attack Vector
Network
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

DescriptionCVE.org

Vulnerability in the MySQL Server, MySQL Cluster product of Oracle MySQL (component: Server: Replication). Supported versions that are affected are MySQL Server: 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; MySQL Cluster: 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3 and 26.7.0-26.7.1. Difficult to exploit vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server, MySQL Cluster. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server, MySQL Cluster. CVSS 3.1 Base Score 4.4 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H).

Threat Intelligence Overview

EPSS Score
0.3%
Top 74% exploitable
Prevalence
Ubiquitous
MySQL is among the most widely deployed databases worldwide
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +22
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Vendor StatusVendor

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