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Mysql ServerDatabase / datastore · Oracle

CVE-2026-34271

MEDIUM · 6.5 CVSS v3.1 Published 2026-04-21
Fix available
A fix is available. Upgrade to after 9.6.0 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Group Replication Plugin). Supported versions that are affected are 8.0.0-8.0.45, 8.4.0-8.4.8 and 9.0.0-9.6.0. 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).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A vulnerability in the MySQL Server Group Replication Plugin allows low-privileged attackers with network access to cause a complete denial of service via crash or hang of the MySQL Server. The vulnerability affects Group Replication functionality which is used for synchronous replication and high availability configurations.

MitigationUpgrade MySQL Server to a patched version beyond 8.0.45, 8.4.8, or 9.6.0 as appropriate for the deployed major version line. If immediate patching is not possible, restrict network access to MySQL ports and limit privileged database accounts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Mysql ServerDatabase / datastore
Affected:>= 8.0.0, <= 8.0.45>= 8.4.0, <= 8.4.8>= 9.0.0, <= 9.6.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check MySQL Server version
    Run 'SELECT VERSION();' or 'mysqld --version' to get the installed MySQL Server version
    Affected if Version is >= 8.0.0 and <= 8.0.45, OR >= 8.4.0 and <= 8.4.8, OR >= 9.0.0 and <= 9.6.0
  2. Verify Group Replication plugin is loaded
    Run 'SHOW PLUGINS;' and look for 'group_replication' in the Status column, or query 'SELECT * FROM information_schema.PLUGINS WHERE PLUGIN_NAME="group_replication";'
    Affected if Group Replication plugin is present and active (Status is 'ACTIVE')
  3. Check Group Replication configuration
    Run 'SHOW VARIABLES LIKE "group_replication%";' to see if Group Replication is configured
    Affected if Group Replication is enabled (group_replication_group_name is set) or the server is part of a replication group
  4. Determine network exposure
    Check if MySQL port (default 3306) is accessible from untrusted networks using tools like 'netstat -tlnp' or 'ss -tlnp'
    Affected if MySQL is listening on a publicly accessible network interface or an interface reachable by low-privileged attackers

User is affected if MySQL Server version falls within the affected ranges AND Group Replication plugin is enabled AND the server is network-accessible to untrusted users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 9.6.0
Interim mitigation

Upgrade MySQL Server to a patched version beyond 8.0.45, 8.4.8, or 9.6.0 as appropriate for the deployed major version line. If immediate patching is not possible, restrict network access to MySQL ports and limit privileged database accounts.

Recommended fix Moderate confidence

MySQL Server 8.0.46 (or later), 8.4.9 (or later), 9.6.1 (or later)

  1. 1. Identify the MySQL Server version currently running: `mysql --version`
  2. 2. Stop the MySQL Server service before upgrading
  3. 3. For RHEL/CentOS/Fedora: Run `sudo yum update mysql-server` or `sudo dnf upgrade mysql-server`
  4. 4. For Debian/Ubuntu: Run `sudo apt-get update && sudo apt-get install mysql-server`
  5. 5. For Windows: Download and install the updated MySQL installer from https://dev.mysql.com/downloads/mysql/
  6. 6. For generic Linux: Download the appropriate MySQL repository package and upgrade: `sudo yum install mysql-community-server` or use the MySQL Yum Repository
  7. 7. After upgrade, start the MySQL Server service
  8. 8. Verify the new version is running: `mysql --version`
Caveat Review Oracle MySQL 8.0.46, 8.4.9, and 9.6.1 release notes for any breaking changes; minor version upgrades typically have low risk but always test in non-production first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mysql Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-34271 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data