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Mysql ServerDatabase / datastore · Oracle

CVE-2025-21540

MEDIUM · 5.4 CVSS v3.1 Published 2025-01-21
Fix available
A fix is available. Upgrade to after 9.1.0 or later.
See remediation →
60/100
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: Security: Privileges). 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 low privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized update, insert or delete access to some of MySQL Server accessible data as well as unauthorized read access to a subset of MySQL Server accessible data. CVSS 3.1 Base Score 5.4 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N).

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

This is a privilege authorization bypass in MySQL Server's Security: Privileges component. A low-privileged attacker with network access can exploit this to gain unauthorized read, insert, update, or delete access to a subset of MySQL Server data that should be restricted. The vulnerability affects MySQL 8.0.x (≤8.0.40), 8.4.x (≤8.4.3), and 9.x (≤9.1.0).

MitigationApply the relevant Oracle Critical Patch Update (CPU) for CVE-2025-21540 to upgrade MySQL Server to a patched version. Until the patch is applied, restrict network access to MySQL and follow least-privilege principles for database user 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, <= 8.0.40>= 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
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

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

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
    Execute `SELECT VERSION();` from a MySQL client or run `mysqld --version` from the command line
    Affected if The version displayed is 8.0.x where x ≤ 40, 8.4.x where x ≤ 3, or 9.x where x ≤ 1.0 (including 9.1.0 itself)
  2. Verify network listening status
    Check MySQL configuration files (my.cnf or my.ini) for `bind-address` setting and run query `SHOW VARIABLES LIKE 'skip-networking';`
    Affected if `skip-networking` is OFF or unset AND `bind-address` is set to 0.0.0.0 or a publicly accessible IP address, indicating MySQL accepts remote connections
  3. Confirm low-privilege user existence
    Execute `SELECT user, host FROM mysql.user WHERE Select_priv='Y' OR Insert_priv='Y' OR Update_priv='Y' OR Delete_priv='Y';` to list users with data access privileges
    Affected if Any database user with data manipulation privileges (SELECT, INSERT, UPDATE, DELETE) exists and is accessible over the network, creating a potential attack vector

You are affected if your MySQL version falls within the vulnerable ranges (8.0.0-8.0.40, 8.4.0-8.4.3, 9.0.0-9.1.0) and the server accepts network connections from untrusted sources.

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 relevant Oracle Critical Patch Update (CPU) for CVE-2025-21540 to upgrade MySQL Server to a patched version. Until the patch is applied, restrict network access to MySQL and follow least-privilege principles for database user accounts.

Recommended fix High confidence

MySQL 8.0.41+ / 8.4.4+ / 9.2.0+ (depending on your major version branch)

  1. 1. Identify 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 appropriate MySQL Server release from https://dev.mysql.com/downloads/mysql/
  6. 6. Follow standard MySQL upgrade procedures for your platform
  7. 7. After upgrade, verify version with: SELECT VERSION();
  8. 8. Test application functionality to ensure compatibility
Caveat Standard MySQL upgrade considerations apply - review MySQL upgrade documentation for any migration steps required between major versions

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-2025-21540 in production — separate from our analysis above.

No notes yet

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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