CVE-2026-21929
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 · uneditedVulnerability in the MySQL Server product of Oracle MySQL (component: Server: Parser). Supported versions that are affected are 9.0.0-9.5.0. Difficult to exploit 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 5.3 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/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 · moderate confidenceA denial of service vulnerability exists in the MySQL Server Parser component affecting versions 9.0.0 through 9.5.0. The vulnerability is difficult to exploit (high attack complexity) and allows low-privileged attackers with network access via multiple protocols to cause MySQL Server to hang or repeatedly crash.
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>= 9.0.0, <= 9.5.0CVSS 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
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:H/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 checksWork through these to decide whether this CVE applies to you.
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Check installed MySQL Server versionRun 'SELECT VERSION();' or 'mysql --version' from the MySQL client or command lineAffected if Version is 9.0.0 through 9.5.0 inclusive
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Verify MySQL network listener is enabledCheck MySQL configuration files (my.cnf or my.ini) for 'bind-address' setting or run 'SHOW VARIABLES LIKE 'hostname''; also check if port 3306 is listening with 'netstat -an | grep 3306' or 'ss -tlnp | grep 3306'Affected if MySQL is listening on a network interface (0.0.0.0 or specific IP rather than 127.0.0.1)
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Identify low-privileged MySQL users with network accessRun 'SELECT user, host, plugin FROM mysql.user WHERE authentication_string IS NOT NULL;' and review user privileges with 'SHOW GRANTS FOR 'username'@'host';' for any non-admin usersAffected if There are user accounts other than root/admin with network-accessible hosts ('%' or non-localhost) and limited privileges
A user is affected if their MySQL Server version is between 9.0.0 and 9.5.0, the server accepts network connections, and low-privileged network-accessible user accounts exist.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataApply Oracle's official MySQL security patches for this vulnerability. If no patch is immediately available, restrict network access to MySQL servers and limit low-privileged user permissions as a compensating control.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-21929 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-21929 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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