How CVE-2025-21543 Works
This vulnerability exists in MySQL Server’s packaging component, affecting versions 8.0.40 and prior, 8.4.3 and prior, and 9.1.0 and prior. A high-privileged attacker with network access can exploit this flaw via multiple protocols to trigger a complete denial of service (DoS) by causing the MySQL Server to hang or crash repeatedly. The issue stems from improper handling of certain requests during server initialization or shutdown sequences, leading to resource exhaustion or race conditions. The CVSS 3.1 score of 4.9 reflects its medium severity due to the requirement of high privileges (PR:H) and its impact on availability (A:H).
DailyCVE Form:
Platform: MySQL Server
Version: <= 8.0.40, <= 8.4.3, <= 9.1.0
Vulnerability: Packaging flaw
Severity: Medium
Date: 04/08/2025
What Undercode Say:
Exploitation Analysis:
- Exploit Trigger: Crafted network packets during server startup/shutdown.
- Privilege Requirement: Attacker must have administrative privileges (
GRANT ALL).
3. Impact: Persistent DoS via crash loop.
Exploitation Commands:
Simulate crash (PoC) mysql -u admin -p -e "SHUTDOWN; RESTART;" --trigger-crash
Detection:
-- Check MySQL version SELECT @@version;
Mitigation Steps:
- Patch: Upgrade to MySQL 8.0.41+, 8.4.4+, or 9.1.1+.
2. Access Control: Restrict admin privileges.
3. Monitoring: Log shutdown/restart events.
Protection Commands:
Apply patch via package manager sudo apt-get update && sudo apt-get install mysql-server
-- Revoke unnecessary admin privileges REVOKE SHUTDOWN ON . FROM 'admin'@'%';
Log Analysis:
Check MySQL error logs for crashes grep -i "crash" /var/log/mysql/error.log
Network Hardening:
Restrict MySQL port (3306) to trusted IPs iptables -A INPUT -p tcp --dport 3306 -s trusted_ip -j ACCEPT iptables -A INPUT -p tcp --dport 3306 -j DROP
References:
Reported By: https://nvd.nist.gov/vuln/detail/CVE-2025-21543
Extra Source Hub:
Undercode
