CVE-2026-34319: MySQL Shell Core Client DoS Vulnerability

CVE-2026-34319 Overview

A denial of service vulnerability exists in the MySQL Shell product of Oracle MySQL, specifically in the Shell: Core Client component. This vulnerability allows a low-privileged attacker with local access to the infrastructure where MySQL Shell executes to cause a hang or frequently repeatable crash of the application, resulting in a complete denial of service condition. The attack requires human interaction from a person other than the attacker to succeed.

Critical Impact

Successful exploitation can result in complete denial of service (DoS) of MySQL Shell, causing application hangs or crashes that disrupt database administration and management operations.

Affected Products

• MySQL Shell versions 8.0.0 through 8.0.45
• MySQL Shell versions 8.4.0 through 8.4.8
• MySQL Shell versions 9.0.0 through 9.6.0

Discovery Timeline

• 2026-04-21 - CVE CVE-2026-34319 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-34319

Vulnerability Analysis

This vulnerability affects the Shell: Core Client component of Oracle MySQL Shell. The flaw is categorized under CWE-204 (Observable Response Discrepancy), indicating that the vulnerability may involve improper handling of responses that allows an attacker to manipulate application behavior. The vulnerability is easily exploitable by a local attacker with low privileges, though successful exploitation requires user interaction from another party. The impact is limited to availability, with no effect on confidentiality or integrity of data.

Root Cause

The root cause relates to improper handling within the MySQL Shell Core Client component. The vulnerability appears to stem from an observable response discrepancy (CWE-204) that can be leveraged to trigger denial of service conditions. This type of weakness typically involves the application responding in detectably different ways to various inputs, which can be abused to cause resource exhaustion or crash states.

Attack Vector

The attack vector is local, requiring the attacker to have logon access to the infrastructure where MySQL Shell executes. The attacker must possess low-level privileges on the system, and the attack additionally requires human interaction from a person other than the attacker. Once these conditions are met, the attacker can exploit the vulnerability to cause MySQL Shell to hang or crash repeatedly.

The exploitation mechanism involves triggering specific conditions within the Core Client component that lead to an unrecoverable state. Detailed technical exploitation steps can be found in the Oracle Security Alert April 2026.

Detection Methods for CVE-2026-34319

Indicators of Compromise

• Unexpected crashes or hangs of MySQL Shell processes
• Repeated restarts of MySQL Shell client sessions without user initiation
• Error logs showing abnormal termination of the mysqlsh process

Detection Strategies

• Monitor MySQL Shell process stability and track crash frequency
• Implement logging to capture MySQL Shell session terminations and restart patterns
• Set up alerting for unusual patterns of MySQL Shell process behavior on database administration systems

Monitoring Recommendations

• Enable detailed logging for MySQL Shell client operations
• Monitor system logs for core dumps or crash reports associated with MySQL Shell
• Implement application performance monitoring for MySQL Shell instances in production environments

How to Mitigate CVE-2026-34319

Immediate Actions Required

• Review and restrict local access to systems running MySQL Shell
• Limit the number of users with logon privileges to database infrastructure
• Update MySQL Shell to the latest patched version as soon as available from Oracle

Patch Information

Oracle has addressed this vulnerability in their April 2026 Critical Patch Update. Organizations should apply the appropriate security patches by consulting the Oracle Security Alert April 2026 for specific patch details and update instructions.

Workarounds

• Restrict local system access to MySQL Shell installations to only essential administrative personnel
• Implement strict access controls on database management infrastructure
• Consider network segmentation to limit access to systems running MySQL Shell

# Verify MySQL Shell version and check if update is required
mysqlsh --version

# Restrict file permissions on MySQL Shell installation (Linux example)
chmod 750 /usr/bin/mysqlsh
chown root:dba /usr/bin/mysqlsh