CVE-2025-21497: Oracle MySQL Server InnoDB DOS Vulnerability

CVE-2025-21497 Overview

CVE-2025-21497 is a vulnerability in the InnoDB component of Oracle MySQL Server. Affected versions include MySQL Server 8.0.40 and prior, 8.4.3 and prior, and 9.1.0 and prior. The flaw allows a high-privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful exploitation can cause a hang or repeatable crash resulting in complete denial of service. Attackers can also achieve unauthorized update, insert, or delete access to a subset of MySQL Server data. Oracle addressed the issue in the January 2025 Critical Patch Update. The vulnerability is classified under [CWE-346] Origin Validation Error.

Critical Impact
Authenticated attackers with high privileges can trigger a complete denial of service and modify accessible MySQL Server data over the network.

Affected Products

Oracle MySQL Server 8.0.40 and prior
Oracle MySQL Server 8.4.3 and prior
Oracle MySQL Server 9.1.0 and prior

Discovery Timeline

2025-01-21 - CVE-2025-21497 published to NVD alongside Oracle's January 2025 Critical Patch Update
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-21497

Vulnerability Analysis

The vulnerability resides in the InnoDB storage engine, MySQL's default transactional engine responsible for ACID compliance, row-level locking, and crash recovery. An authenticated attacker holding high privileges can send crafted requests through supported MySQL protocols to trigger the flaw. The result is either a server hang or a repeatable crash, producing full denial of service for downstream applications relying on the database.

Beyond availability impact, the vulnerability permits unauthorized modification of a subset of data accessible to MySQL Server. Attackers can perform update, insert, or delete operations outside their intended authorization boundary. Confidentiality is not affected because the flaw does not expose data reads.

The EPSS score is 0.469% (39.787 percentile), reflecting a low observed exploitation likelihood as of the latest scoring window.

Root Cause

The issue is categorized under [CWE-346] Origin Validation Error. InnoDB fails to properly validate the origin or trustworthiness of certain inputs or operations, allowing a privileged attacker to bypass expected boundary checks. This validation gap enables both the data integrity impact and the denial-of-service condition when malformed or unexpected operations reach the storage engine.

Attack Vector

Exploitation requires network access to the MySQL Server instance and a high-privileged database account. The attacker can use multiple MySQL protocols to deliver the payload. No user interaction is required, and the attack complexity is low once the privilege requirement is satisfied. Because the vulnerability sits in InnoDB, exploitation targets fundamental storage-engine operations rather than a specific SQL syntax feature.

Oracle has not published detailed exploitation mechanics for this issue. Refer to the Oracle Critical Patch Update January 2025 advisory for the vendor's disclosure. There is no verified public proof-of-concept exploit at this time.

Detection Methods for CVE-2025-21497

Indicators of Compromise

Unexpected mysqld process crashes or hangs correlated with authenticated sessions from high-privilege accounts
InnoDB assertion failures or fatal errors recorded in the MySQL error log
Unexplained INSERT, UPDATE, or DELETE operations on tables not typically modified by the involved account
Repeated abnormal disconnects or restart events on the database service

Detection Strategies

Monitor MySQL error logs for InnoDB-related crash signatures and repeated recovery events
Enable and review the MySQL general query log or audit log for anomalous privileged operations
Correlate authentication events for administrative accounts with subsequent service instability
Baseline normal DML activity per privileged account and alert on deviations

Monitoring Recommendations

Forward MySQL error, audit, and slow query logs to a centralized SIEM for correlation
Track service uptime metrics for mysqld and alert on unexpected restarts
Monitor network connections to port 3306 and any alternate MySQL protocol endpoints for unusual client origins
Alert on privilege escalation events and grants issued to database accounts

How to Mitigate CVE-2025-21497

Immediate Actions Required

Apply the fixes released in the Oracle January 2025 Critical Patch Update to all affected MySQL Server instances
Inventory MySQL deployments across production, staging, and development environments to confirm patch coverage
Audit and reduce accounts with high privileges such as SUPER, SYSTEM_VARIABLES_ADMIN, or DBA-equivalent roles
Restrict network exposure of MySQL Server to trusted management and application networks only

Patch Information

Oracle addressed CVE-2025-21497 in the Oracle Critical Patch Update January 2025. Upgrade MySQL Server to a version released after 8.0.40, 8.4.3, or 9.1.0 as appropriate for your deployment channel. NetApp products bundling MySQL are covered in NetApp Security Advisory NTAP-20250131-0004; apply vendor-specific updates when they become available.

Workarounds

Enforce least privilege by revoking unnecessary administrative grants from application and service accounts
Restrict mysqld bind address and firewall access to known-good client subnets
Require strong authentication and rotate credentials for high-privilege database accounts
Deploy database activity monitoring to detect and block anomalous privileged queries until patching is complete

bash

# Example: restrict MySQL bind address and revoke excess privileges
# /etc/mysql/mysql.conf.d/mysqld.cnf
[mysqld]
bind-address = 10.0.0.15
skip_networking = OFF

# Revoke high-risk privileges from a non-DBA account
REVOKE SUPER, SYSTEM_VARIABLES_ADMIN ON *.* FROM 'app_user'@'%';
FLUSH PRIVILEGES;