CVE-2022-31625: PHP PostgreSQL Extension RCE Vulnerability

CVE-2022-31625 Overview

CVE-2022-31625 is a memory corruption vulnerability affecting PHP versions 7.4.x below 7.4.30, 8.0.x below 8.0.20, and 8.1.x below 8.1.7. When using the PostgreSQL database extension, supplying invalid parameters to parametrized queries may lead to PHP attempting to free memory using uninitialized data as pointers. This vulnerability could result in remote code execution (RCE) or denial of service conditions.

Critical Impact

This vulnerability enables attackers to potentially achieve remote code execution or cause denial of service by exploiting improper memory handling in PHP's PostgreSQL extension when processing malformed query parameters.

Affected Products

• PHP versions 7.4.x below 7.4.30
• PHP versions 8.0.x below 8.0.20
• PHP versions 8.1.x below 8.1.7
• Debian Linux 10.0
• Debian Linux 11.0

Discovery Timeline

• 2022-06-16 - CVE-2022-31625 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-31625

Vulnerability Analysis

This vulnerability resides in PHP's PostgreSQL database extension (pgsql) and involves improper memory management during parametrized query processing. The core issue stems from the use of uninitialized memory pointers, which are subsequently passed to memory deallocation functions. When invalid parameters are supplied to parametrized queries, the extension fails to properly initialize memory structures before attempting to free them.

The vulnerability is classified under CWE-590 (Free of Memory not on the Heap) and CWE-763 (Release of Invalid Pointer or Reference), indicating that the root cause involves improper pointer management during memory operations. The network-accessible nature of this vulnerability means that web applications using PHP with PostgreSQL backends are potentially at risk if they process user-controlled input in database queries.

Successful exploitation requires the attacker to supply specially crafted invalid parameters to parametrized PostgreSQL queries. While the attack complexity is high due to the specific conditions required for exploitation, the potential impact is severe—attackers could achieve arbitrary code execution within the context of the PHP process or cause application crashes leading to denial of service.

Root Cause

The vulnerability originates from improper initialization of memory structures within PHP's PostgreSQL extension. Specifically, when processing parametrized queries with invalid parameters, the extension allocates memory for parameter handling but fails to properly initialize the associated pointer variables. When the cleanup routines execute, they attempt to free memory using these uninitialized pointers, leading to undefined behavior.

This type of "use of uninitialized pointer" vulnerability can cause the application to attempt freeing arbitrary memory addresses, potentially corrupting heap metadata or other critical data structures. The dual CWE classification (CWE-590 and CWE-763) reflects both the improper memory freeing operation and the use of invalid pointer references.

Attack Vector

The attack vector is network-based, meaning remote attackers can potentially exploit this vulnerability through web applications that utilize PHP with the PostgreSQL extension. The exploitation scenario typically involves:

1. Identifying a PHP application that uses PostgreSQL parametrized queries
2. Supplying carefully crafted invalid parameters through user input channels
3. Triggering the vulnerable code path that leads to uninitialized pointer usage
4. Achieving either code execution through memory corruption or denial of service through application crash

While no authenticated access is required, the attack complexity is elevated due to the specific conditions needed to trigger the vulnerability successfully. The vulnerability affects the confidentiality, integrity, and availability of the system.

Detection Methods for CVE-2022-31625

Indicators of Compromise

• Unexpected PHP process crashes or segmentation faults when processing PostgreSQL queries
• Anomalous memory access patterns in PHP error logs related to the pgsql extension
• Application instability or unexpected behavior following database query operations
• Core dump files indicating memory corruption in PHP processes

Detection Strategies

• Monitor PHP error logs for segmentation faults, memory corruption errors, or pgsql extension failures
• Implement application-level logging to track parametrized query execution and parameter validation
• Deploy web application firewalls (WAF) with rules to detect malformed database query parameters
• Use runtime application self-protection (RASP) solutions to detect anomalous memory operations

Monitoring Recommendations

• Enable verbose logging for PHP's PostgreSQL extension to capture parameter processing errors
• Configure system monitoring to alert on PHP process crashes or abnormal terminations
• Implement database query auditing to identify suspicious or malformed parametrized queries
• Set up memory monitoring for PHP-FPM or PHP processes to detect unusual allocation patterns

How to Mitigate CVE-2022-31625

Immediate Actions Required

• Upgrade PHP to version 7.4.30 or later (for 7.4.x branch)
• Upgrade PHP to version 8.0.20 or later (for 8.0.x branch)
• Upgrade PHP to version 8.1.7 or later (for 8.1.x branch)
• Apply vendor security patches for Debian and other affected distributions
• Review and validate all PostgreSQL parametrized query input handling in applications

Patch Information

Security patches addressing CVE-2022-31625 have been released by PHP and various Linux distributions. The fix ensures proper initialization of memory structures before any deallocation operations occur in the PostgreSQL extension. Administrators should consult the following resources for distribution-specific patches:

• PHP Bug Report #81720 - Original bug report with technical details
• Debian Security Advisory DSA-5179 - Debian stable release patches
• Debian LTS Announcement - Long-term support updates
• Gentoo GLSA 202209-20 - Gentoo Linux security advisory
• NetApp Security Advisory - NetApp product updates

Workarounds

• Implement strict input validation for all parameters passed to PostgreSQL parametrized queries
• Consider using prepared statements with robust parameter type checking at the application level
• Deploy web application firewalls to filter potentially malicious query parameters
• Isolate PHP processes using containers or sandboxing to limit impact of potential exploitation
• Monitor and limit resource consumption of PHP processes to mitigate denial of service impact

# Verify PHP version after patching
php -v

# Check PostgreSQL extension version
php -m | grep pgsql

# Verify patched version on Debian/Ubuntu
apt-cache policy php8.1-pgsql