CVE-2024-8929: PHP Information Disclosure Vulnerability

CVE-2024-8929 Overview

CVE-2024-8929 is an out-of-bounds read vulnerability affecting PHP's MySQL client implementation. A hostile MySQL server can exploit this flaw to force the PHP client to disclose contents of its heap memory, potentially exposing sensitive data from other SQL requests and information belonging to different users on the same server. This vulnerability represents a significant confidentiality risk in environments where PHP applications connect to untrusted or compromised MySQL servers.

Critical Impact

A malicious MySQL server can extract heap memory contents from PHP clients, potentially exposing sensitive data from other SQL requests and different users sharing the same PHP process.

Affected Products

• PHP versions 8.1.* before 8.1.31
• PHP versions 8.2.* before 8.2.26
• PHP versions 8.3.* before 8.3.14

Discovery Timeline

• November 22, 2024 - CVE-2024-8929 published to NVD
• November 03, 2025 - Last updated in NVD database

Technical Details for CVE-2024-8929

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-Bounds Read) and affects the MySQL client component within PHP. The flaw allows a hostile MySQL server to manipulate the protocol communication in a way that causes the PHP client to read beyond the intended memory boundaries. When exploited, the client inadvertently discloses heap memory contents back to the attacker-controlled server.

The attack requires adjacent network access and involves some complexity, as the attacker must either control a MySQL server that the victim connects to or perform a man-in-the-middle attack on an existing connection. While the attack requires low-level privileges, successful exploitation can lead to cross-scope information disclosure, affecting data confidentiality beyond the immediate application context.

Root Cause

The vulnerability stems from improper bounds checking in PHP's MySQL client implementation when processing responses from a MySQL server. The client fails to adequately validate buffer boundaries when handling certain server responses, leading to an out-of-bounds read condition. This allows heap memory data to be leaked back to the server in subsequent protocol exchanges.

Attack Vector

The attack requires the adversary to operate a malicious MySQL server or compromise an existing one that PHP applications connect to. The hostile server sends specially crafted responses that trigger the out-of-bounds read in the PHP client. The leaked heap memory may contain:

• Data from previous SQL queries executed by the same PHP process
• Session information from other users of a shared PHP environment
• Application secrets, credentials, or other sensitive information stored in memory
• Internal application state and configuration data

The adjacent network attack vector indicates that the attacker typically needs to be on the same network segment or have the ability to intercept MySQL connections to position their malicious server between the client and legitimate database infrastructure.

Detection Methods for CVE-2024-8929

Indicators of Compromise

• Unexpected network connections from PHP processes to unknown MySQL servers
• Anomalous MySQL protocol traffic patterns, particularly unusual response sizes or sequences
• PHP applications connecting to MySQL endpoints outside of expected IP ranges
• Evidence of MySQL traffic interception or DNS spoofing targeting database connections

Detection Strategies

• Monitor PHP application logs for connection errors or unexpected MySQL server responses
• Implement network monitoring to detect connections to unauthorized MySQL endpoints
• Deploy intrusion detection rules to identify suspicious MySQL protocol anomalies
• Audit DNS configurations to prevent redirection of database hostnames to malicious servers

Monitoring Recommendations

• Enable detailed logging for all MySQL connections from PHP applications
• Configure alerting for PHP processes connecting to new or unauthorized database servers
• Monitor for unusual memory usage patterns in PHP worker processes
• Review network segmentation to ensure database traffic flows through monitored paths

How to Mitigate CVE-2024-8929

Immediate Actions Required

• Upgrade PHP to patched versions: 8.1.31, 8.2.26, or 8.3.14 or later
• Audit all MySQL connection configurations to ensure connections only target trusted servers
• Implement network-level controls to restrict PHP application database connectivity
• Review and harden DNS configurations to prevent database hostname hijacking

Patch Information

PHP has released security patches addressing this vulnerability. Organizations should upgrade to the following minimum versions:

• PHP 8.1 branch: Upgrade to 8.1.31 or later
• PHP 8.2 branch: Upgrade to 8.2.26 or later
• PHP 8.3 branch: Upgrade to 8.3.14 or later

Detailed patch information is available in the PHP Security Advisory on GitHub. Additional vendor-specific guidance is available from Debian LTS and NetApp.

Workarounds

• Ensure MySQL connections are made exclusively to trusted, verified database servers
• Implement TLS/SSL for all MySQL connections with proper certificate validation
• Use network firewalls to restrict outbound MySQL connections from PHP servers to only approved database hosts
• Consider deploying a MySQL proxy with connection auditing capabilities

# Configuration example - Restrict MySQL connections via iptables
# Allow connections only to known MySQL server at 10.0.1.50
iptables -A OUTPUT -p tcp --dport 3306 -d 10.0.1.50 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 3306 -j DROP