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Mysql ServerDatabase / datastore · Oracle

CVE-2025-21555

MEDIUM · 5.5 CVSS v3.1 Published 2025-01-21
Fix available
A fix is available. Upgrade to after 9.1.0 or later.
See remediation →
61/100
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: InnoDB). Supported versions that are affected are 8.0.40 and prior, 8.4.3 and prior and 9.1.0 and prior. Easily exploitable vulnerability allows high 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 as well as unauthorized update, insert or delete access to some of MySQL Server accessible data. CVSS 3.1 Base Score 5.5 (Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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 InnoDB storage engine of MySQL Server allows high-privileged attackers with network access to cause denial of service (hang or crash) and gain unauthorized insert, update, or delete access to some accessible data. The vulnerability affects MySQL versions 8.0.40 and prior, 8.4.3 and prior, and 9.1.0 and prior.

MitigationApply the appropriate MySQL Server patch or upgrade to a non-vulnerable version (beyond 8.0.40, 8.4.3, or 9.1.0 depending on your branch) to remediate this vulnerability.

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, <= 8.0.40>= 8.4.0, <= 8.4.3>= 9.0.0, <= 9.1.0

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
High
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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. Determine installed MySQL Server version
    Execute 'SELECT VERSION();' in the MySQL client or run 'mysqld --version' from the command line
    Affected if The version number returned is 8.0.x where x <= 40, 8.4.x where x <= 3, or 9.0.x or 9.1.x (any patch level within 9.0.0 to 9.1.0)
  2. Confirm InnoDB storage engine is in use
    Run 'SHOW ENGINES;' and verify InnoDB shows as 'DEFAULT' or 'YES' in the Support column
    Affected if InnoDB is enabled (which is the default for MySQL installations)
  3. Verify InnoDB is the active engine for databases
    Run 'SHOW TABLE STATUS FROM <database_name>;' for any user databases and check the Engine column, or query 'SELECT TABLE_SCHEMA, TABLE_NAME, ENGINE FROM INFORMATION_SCHEMA.TABLES WHERE ENGINE = 'InnoDB';'
    Affected if Any tables in the environment use the InnoDB storage engine (common default)
  4. Check MySQL network binding configuration
    Examine the my.cnf or my.ini configuration file for 'bind-address' setting, or run 'SHOW VARIABLES LIKE 'bind_address';'
    Affected if The server is bound to a network-accessible IP address (0.0.0.0 or a specific IP rather than 127.0.0.1)
  5. Confirm high-privileged user access exists
    Review user grants with 'SELECT user, host, plugin FROM mysql.user;' and check for any non-local accounts with broad privileges
    Affected if There are MySQL users with network access and elevated privileges (e.g., root, DBA-level accounts)

The environment is affected if the MySQL Server version falls within 8.0.0-8.0.40, 8.4.0-8.4.3, or 9.0.0-9.1.0, InnoDB is in use (the default), and the server is network-accessible with high-privileged accounts present.

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 9.1.0
Interim mitigation

Apply the appropriate MySQL Server patch or upgrade to a non-vulnerable version (beyond 8.0.40, 8.4.3, or 9.1.0 depending on your branch) to remediate this vulnerability.

Recommended fix High confidence

MySQL 8.0.41 (or later 8.0.x), MySQL 8.4.4 (or later 8.4.x), or MySQL 9.2.0 (or later 9.x)

  1. 1. Identify the current MySQL Server version using: SELECT VERSION();
  2. 2. For MySQL 8.0.x: Upgrade to MySQL 8.0.41 or later
  3. 3. For MySQL 8.4.x: Upgrade to MySQL 8.4.4 or later
  4. 4. For MySQL 9.x: Upgrade to MySQL 9.2.0 or later
  5. 5. Download the target version from https://dev.mysql.com/downloads/mysql/
  6. 6. Perform a full backup of all databases before upgrading
  7. 7. Review the MySQL upgrade guide at https://dev.mysql.com/doc/refman/en/upgrading.html
  8. 8. Stop the MySQL service, install the new version, and restart the service
Caveat Review Oracle's upgrade notes for potential incompatibilities; test in staging environment before production deployment

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

Fix this in Mysql Server Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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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-2025-21555 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