CVE-2025-21490
📋 TL;DR
This vulnerability in MySQL Server's InnoDB component allows high-privileged attackers with network access to cause a denial of service by crashing or hanging the server. It affects MySQL 8.0.40 and prior, 8.4.3 and prior, and 9.1.0 and prior versions. Attackers need administrative database privileges but can exploit it remotely via multiple protocols.
💻 Affected Systems
- Oracle MySQL Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete MySQL Server outage causing application downtime and service disruption until server restart.
Likely Case
Targeted DoS attacks against MySQL databases by malicious insiders or compromised admin accounts.
If Mitigated
Limited impact due to proper access controls and network segmentation preventing unauthorized admin access.
🎯 Exploit Status
CVSS indicates 'Easily exploitable' but requires high privilege access. No public exploit code identified in references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: MySQL 8.0.41, 8.4.4, 9.1.1 or later
Vendor Advisory: https://www.oracle.com/security-alerts/cpujan2025.html
Restart Required: Yes
Instructions:
1. Backup databases and configuration. 2. Download patched version from Oracle. 3. Stop MySQL service. 4. Install updated version. 5. Restart MySQL service. 6. Verify functionality.
🔧 Temporary Workarounds
Restrict Network Access
allLimit MySQL server network exposure to only trusted hosts and applications
# In MySQL config (my.cnf): bind-address = 127.0.0.1
# Or use firewall: sudo ufw deny 3306/tcp
Minimize Admin Privileges
allReduce number of accounts with administrative privileges and implement least privilege
REVOKE ALL PRIVILEGES ON *.* FROM 'admin_user'@'%';
GRANT SELECT, INSERT, UPDATE, DELETE ON specific_db.* TO 'app_user'@'specific_host';
🧯 If You Can't Patch
- Implement strict network segmentation to isolate MySQL servers from untrusted networks
- Enforce strong authentication and monitor for unusual admin account activity
🔍 How to Verify
Check if Vulnerable:
Check MySQL version: SELECT VERSION(); and compare against affected versionsCheck Version:
mysql --version OR SELECT VERSION();Verify Fix Applied:
Verify version is 8.0.41+, 8.4.4+, or 9.1.1+ and test server stability under load📡 Detection & Monitoring
Log Indicators:
- Unexpected MySQL crashes or restarts
- Multiple connection attempts from admin accounts
- Error logs showing InnoDB corruption or crashes
Network Indicators:
- Unusual traffic patterns to MySQL port 3306 from unexpected sources
- Multiple rapid connections followed by service disruption
SIEM Query:
source="mysql.log" ("crash" OR "shutdown" OR "restart") AND NOT (user="system" OR process="scheduled")