Hayden

On February 13, 2025, the PostgreSQL community disclosed a critical SQL injection vulnerability that deserves immediate attention from database administrators worldwide. CVE-2025-1094 affects character encoding handling mechanisms and poses particular risks for systems using certain Asian character encodings.

This vulnerability was discovered by Stephen Fewer, Principal Security Researcher at Rapid7, during research into another vulnerability (CVE-2024-12356). The discovery highlights the interconnected nature of security vulnerabilities and the critical importance of robust input validation in database systems.

 

 

1. Root Cause Analysis of CVE-2025-1094

The core issue lies in PostgreSQL’s libpq library string escaping functions, which fail to properly neutralize quoting syntax under specific conditions. The affected functions include:

  • PQescapeLiteral() – Escapes string literals
  • PQescapeIdentifier() – Escapes identifiers
  • PQescapeString() – Escapes general strings
  • PQescapeStringConn() – Connection-specific string escaping

The vulnerability becomes particularly dangerous when combined with specific multibyte character encoding configurations, creating a pathway for SQL injection attacks.

Encoding Risk Matrix

Configuration Client Encoding Server Encoding Risk Level
High Risk BIG5 EUC_TW Critical
High Risk BIG5 MULE_INTERNAL Critical
Safe UTF-8 UTF-8 Low
Safe LATIN1 LATIN1 Low

BIG5 is primarily used for Traditional Chinese characters, while EUC_TW and MULE_INTERNAL are Extended Unix Code for Taiwan and PostgreSQL’s internal multibyte encoding, respectively.

 

 

2. Attack Scenarios and Security Impact

CVE-2025-1094 enables attackers to escalate beyond simple SQL injection to achieve arbitrary code execution on the target system.

Attack Chain

  1. Initial Vector: Attacker sends malicious input containing invalid UTF-8 characters
  2. Escape Bypass: PostgreSQL’s escaping functions fail to properly neutralize quoting syntax
  3. Injection Point: Processed results are passed to psql (PostgreSQL interactive terminal)
  4. Code Execution: Attacker leverages psql meta-commands (\!) to execute operating system shell commands
-- Attack example (actual payload would be binary data)
SELECT 'malicious_string'; \! whoami; --

This attack vector allows unauthorized command execution with database user privileges, potentially leading to complete system compromise.

 

 

3. Affected PostgreSQL Versions

The PostgreSQL development team responded quickly with patches across all supported major versions.

Vulnerable Versions

  • PostgreSQL 17 – All versions prior to 17.3
  • PostgreSQL 16 – All versions prior to 16.7
  • PostgreSQL 15 – All versions prior to 15.11
  • PostgreSQL 14 – All versions prior to 14.16
  • PostgreSQL 13 – All versions prior to 13.19

Patched Versions

  • PostgreSQL 17.3 (Released February 13, 2025)
  • PostgreSQL 16.7 (Released February 13, 2025)
  • PostgreSQL 15.11 (Released February 13, 2025)
  • PostgreSQL 14.16 (Released February 13, 2025)
  • PostgreSQL 13.19 (Released February 13, 2025)

Official patch notes are available on the PostgreSQL release page.

 

 

4. Version Detection and Vulnerability Assessment

Before applying patches, accurately identify your current PostgreSQL version and encoding configuration.

Command Line Version Check

# Check PostgreSQL version
psql --version

# Connect and verify version
psql -c "SELECT version();"

Database Version and Encoding Assessment

-- Check version and encoding configuration
SELECT 
    version() as postgresql_version,
    current_setting('server_encoding') as server_encoding,
    current_setting('client_encoding') as client_encoding;

Vulnerability Status Check

-- Determine if current encoding configuration is vulnerable
SELECT 
    CASE 
        WHEN current_setting('client_encoding') = 'BIG5' 
             AND current_setting('server_encoding') IN ('EUC_TW', 'MULE_INTERNAL')
        THEN 'VULNERABLE: Exposed to CVE-2025-1094'
        ELSE 'SAFE: Current encoding configuration is secure'
    END as vulnerability_status;

 

 

5. Step-by-Step Patching and Upgrade Guide

Pre-Upgrade Preparation

Always perform comprehensive backups before upgrading:

# 1. Full cluster backup
pg_dumpall -U postgres > full_backup_$(date +%Y%m%d).sql

# 2. Individual database backup
pg_dump -U postgres -d your_database > db_backup_$(date +%Y%m%d).sql

# 3. Configuration backup
cp $PGDATA/postgresql.conf postgresql.conf.backup
cp $PGDATA/pg_hba.conf pg_hba.conf.backup

Ubuntu/Debian Upgrade Process

# 1. Update package repositories
sudo apt update

# 2. Upgrade PostgreSQL (automatically installs latest patch version)
sudo apt upgrade postgresql postgresql-client

# 3. Verify upgrade
psql --version

# 4. Restart services
sudo systemctl restart postgresql
sudo systemctl status postgresql

CentOS/RHEL/Rocky Linux Upgrade

# 1. Update package information
sudo yum update -y

# 2. Upgrade PostgreSQL
sudo yum update postgresql postgresql-server

# 3. Restart services
sudo systemctl restart postgresql
sudo systemctl status postgresql

Docker Environment Updates

# Update Dockerfile
FROM postgres:17.3  # Change to patched version

# Or update existing container
docker pull postgres:17.3
docker stop your-postgres-container
docker run --name new-postgres-container -d \
  -v your-data-volume:/var/lib/postgresql/data \
  postgres:17.3

 

 

6. Temporary Mitigation and Prevention Strategies

For environments where immediate upgrades aren’t feasible, implement these mitigation measures:

Encoding Configuration Changes

-- Change to safe encoding at database level
ALTER DATABASE your_database SET client_encoding = 'UTF8';

-- Temporary session-level change
SET client_encoding = 'UTF8';

Input Validation Enhancement

# Python example: Input validation
import re

def validate_utf8_input(input_string):
    try:
        # UTF-8 validity check
        input_string.encode('utf-8').decode('utf-8')
        
        # Remove suspicious patterns
        dangerous_patterns = [r'\\', r'\x00', r'\x5c']
        for pattern in dangerous_patterns:
            if re.search(pattern, input_string):
                raise ValueError("Potentially dangerous input detected")
        
        return True
    except UnicodeDecodeError:
        return False

Parameterized Query Implementation

# Safe approach: Parameterized queries
cursor.execute(
    "SELECT * FROM users WHERE username = %s", 
    (user_input,)
)

# Dangerous approach: String concatenation (avoid)
# cursor.execute(f"SELECT * FROM users WHERE username = '{user_input}'")

 

 

7. Cloud Platform Response Strategies

Amazon RDS PostgreSQL

AWS RDS provides automatic patching, but manual upgrades are also available:

# Upgrade RDS instance via AWS CLI
aws rds modify-db-instance \
    --db-instance-identifier your-rds-instance \
    --engine-version 16.7 \
    --apply-immediately

Check Amazon Aurora PostgreSQL updates for latest patch status.

Google Cloud SQL

# Upgrade via gcloud CLI
gcloud sql instances patch your-instance-name \
    --database-version=POSTGRES_16_7

Azure Database for PostgreSQL

Navigate to Azure Portal → [Maintenance] → [Schedule Updates] to schedule upgrades.

 

 

8. Security Monitoring and Log Analysis

Continuous monitoring is essential post-patch:

Suspicious Activity Detection

-- Search PostgreSQL logs for suspicious patterns
SELECT 
    log_time,
    message
FROM pg_log 
WHERE message LIKE '%invalid byte sequence for encoding "UTF8"%'
   OR message LIKE '%psql%'
   OR message LIKE '%meta-command%'
ORDER BY log_time DESC;

Enhanced Logging Configuration

# postgresql.conf modifications
log_statement = 'all'  # Log all SQL statements
log_min_error_statement = error  # Detailed error logging
log_connections = on  # Connection logging
log_disconnections = on  # Disconnection logging

 

 

9. Additional Security Hardening

Network-Level Security

# Firewall configuration to restrict PostgreSQL access
sudo ufw allow from trusted_ip_range to any port 5432
sudo ufw deny 5432

Database Access Control Hardening

-- Remove unnecessary privileges
REVOKE ALL PRIVILEGES ON DATABASE sensitive_db FROM public;

-- Apply principle of least privilege
GRANT CONNECT ON DATABASE app_db TO app_user;
GRANT SELECT, INSERT, UPDATE ON specific_table TO app_user;

 

 

CVE-2025-1094 demonstrates how vulnerabilities can emerge from fundamental features like character encoding. This incident particularly affects organizations using Asian character sets and serves as a reminder of the critical importance of comprehensive security practices. The PostgreSQL community’s rapid response with comprehensive patches across all supported versions demonstrates the strength of open-source security practices. This incident should serve as a catalyst for reviewing and strengthening database security practices across all environments. 🙂

 

References:

 

 

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