CVE-2021-47853: phpPgAdmin RCE Vulnerability

CVE-2021-47853 Overview

CVE-2021-47853 is a remote command execution vulnerability affecting phpPgAdmin version 7.13.0. This vulnerability allows authenticated attackers to execute arbitrary system commands through SQL query manipulation by creating a custom table, uploading a malicious .txt file, and leveraging PostgreSQL's COPY FROM PROGRAM command to execute operating system commands with the application's privileges.

Critical Impact

Authenticated attackers can achieve full remote command execution on vulnerable phpPgAdmin 7.13.0 installations, potentially leading to complete system compromise, data exfiltration, and lateral movement within the network.

Affected Products

• phpPgAdmin 7.13.0

Discovery Timeline

• 2026-01-21 - CVE CVE-2021-47853 published to NVD
• 2026-01-21 - Last updated in NVD database

Technical Details for CVE-2021-47853

Vulnerability Analysis

This vulnerability is classified as Command Injection (CWE-78), which occurs when an application passes unsafe user-controllable data to a system shell. In phpPgAdmin 7.13.0, the web-based PostgreSQL administration tool fails to adequately restrict the use of PostgreSQL's powerful COPY FROM PROGRAM functionality, enabling authenticated users to execute arbitrary operating system commands.

The attack chain requires authenticated access to the phpPgAdmin interface, but once that prerequisite is met, the attacker can leverage legitimate database functionality to break out of the intended application sandbox and execute commands directly on the underlying operating system.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and inadequate restrictions on the PostgreSQL COPY FROM PROGRAM command within the phpPgAdmin interface. The COPY FROM PROGRAM feature in PostgreSQL is designed to allow data to be piped from the output of a shell command directly into a table. While this is a powerful administrative feature, phpPgAdmin 7.13.0 does not properly restrict authenticated users from abusing this functionality.

When users create a custom table and then use the data import functionality with a crafted .txt file, they can inject arbitrary shell commands that are executed by the PostgreSQL backend with the privileges of the PostgreSQL service account.

Attack Vector

The attack is network-based and requires authenticated access to the phpPgAdmin web interface. The exploitation process involves the following steps:

1. An authenticated attacker creates a new database table with an appropriate schema to receive data
2. The attacker prepares a malicious .txt file containing crafted content
3. Using phpPgAdmin's import functionality, the attacker leverages the COPY FROM PROGRAM SQL command
4. The PostgreSQL server executes the specified program/command with its service account privileges
5. Command output can be captured in the created table, allowing data exfiltration or confirmation of successful exploitation

This vulnerability does not require user interaction beyond initial authentication, and it can be exploited remotely over the network. Technical details and proof-of-concept information are available from the Exploit-DB #49736 and the VulnCheck Advisory.

Detection Methods for CVE-2021-47853

Indicators of Compromise

• Unexpected database tables created by non-administrative users with generic names designed to capture command output
• PostgreSQL logs showing COPY FROM PROGRAM statements with shell commands such as id, whoami, cat /etc/passwd, or reverse shell payloads
• Web server access logs showing unusual POST requests to phpPgAdmin data import or SQL execution endpoints
• Suspicious processes spawned as child processes of the PostgreSQL service account

Detection Strategies

• Monitor PostgreSQL audit logs for COPY FROM PROGRAM statements, particularly those containing shell metacharacters or known command injection patterns
• Implement web application firewall (WAF) rules to detect and block SQL injection attempts containing COPY FROM PROGRAM syntax
• Configure SentinelOne to alert on unexpected child processes spawned by PostgreSQL service processes
• Review phpPgAdmin access logs for authenticated sessions performing unusual sequences of table creation followed by data imports

Monitoring Recommendations

• Enable detailed PostgreSQL logging including log_statement = 'all' to capture all SQL queries for forensic analysis
• Configure alerting for any usage of COPY FROM PROGRAM in production environments where this functionality is not required
• Monitor system-level process creation events for commands spawned by the database service user
• Implement network monitoring to detect outbound connections from database servers that may indicate reverse shell activity

How to Mitigate CVE-2021-47853

Immediate Actions Required

• Audit all phpPgAdmin installations and identify any running version 7.13.0
• Restrict network access to phpPgAdmin interfaces using firewall rules to limit exposure to trusted administrators only
• Review PostgreSQL user permissions and remove SUPERUSER privileges from accounts that do not require them
• Consider temporarily disabling phpPgAdmin until a patched version can be deployed or alternative mitigations are in place

Patch Information

Users should check for updated versions of phpPgAdmin via the official GitHub releases page. Organizations should evaluate whether continued use of phpPgAdmin is necessary or if alternative PostgreSQL administration tools with better security postures are available.

Workarounds

• Disable or remove the phpPgAdmin installation if it is not actively required for operations
• Implement strict network segmentation to ensure phpPgAdmin is only accessible from trusted management networks
• Configure PostgreSQL to disallow COPY FROM PROGRAM by restricting file system access permissions or using row-level security policies
• Use a reverse proxy with authentication and request filtering in front of phpPgAdmin to add an additional security layer
• Audit and minimize PostgreSQL user privileges, ensuring application accounts do not have unnecessary permissions

# PostgreSQL configuration to enhance logging (postgresql.conf)
log_statement = 'all'
log_min_duration_statement = 0
log_connections = on
log_disconnections = on

# Restrict phpPgAdmin access via iptables (example)
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP