CVE-2024-23828: Nginxui Nginx UI RCE Vulnerability

CVE-2024-23828 Overview

CVE-2024-23828 is an authenticated arbitrary command execution vulnerability in Nginx-UI, a web interface for managing Nginx configurations. The flaw allows attackers with authenticated access to inject Carriage Return Line Feed (CRLF) sequences when modifying the test_config_cmd or start_cmd configuration values. This results in arbitrary operating system command execution on the host running Nginx-UI. The issue exists because the fixes for CVE-2024-22197 and CVE-2024-22198 were incomplete, leaving the CRLF injection primitive exploitable. The vulnerability is patched in Nginx-UI version 2.0.0.beta.12.

Critical Impact
Authenticated attackers can execute arbitrary commands on the underlying host, leading to full compromise of confidentiality, integrity, and availability of the Nginx server.

Affected Products

Nginx-UI versions prior to 2.0.0.beta.12
Nginx-UI 2.0.0 beta releases beta1 through beta11 (including intermediate patch releases)
Deployments managing Nginx configuration through the Nginx-UI web interface

Discovery Timeline

2024-01-29 - CVE-2024-23828 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-23828

Vulnerability Analysis

The vulnerability is classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component). Nginx-UI exposes configuration fields, including test_config_cmd and start_cmd, through its web management interface. Authenticated users can modify these values, which are later concatenated into command strings executed by the server.

Because the input handling does not neutralize CRLF (\r\n) sequences, an attacker can break out of the intended command context. Injected line terminators allow additional commands to be appended and executed by the underlying shell or command runner. This turns an administrative configuration setting into an arbitrary command execution primitive.

Root Cause

The root cause is incomplete input sanitization on the test_config_cmd and start_cmd configuration parameters. Prior fixes for CVE-2024-22197 and CVE-2024-22198 addressed related injection issues but did not filter or reject embedded CRLF characters. Any authenticated principal with permission to update these settings can supply a payload that survives validation and reaches the command execution path.

Attack Vector

Exploitation requires network access to the Nginx-UI management interface and valid authenticated credentials. An attacker submits a modified test_config_cmd or start_cmd value containing CRLF sequences followed by attacker-controlled commands. When Nginx-UI subsequently invokes the configured command, for example during a configuration test or service start, the appended payload executes with the privileges of the Nginx-UI process. Refer to the GitHub Security Advisory GHSA-qcjq-7f7v-pvc8 for the vendor's technical description.

Detection Methods for CVE-2024-23828

Indicators of Compromise

Unexpected modifications to the Nginx-UI configuration file, particularly the test_config_cmd and start_cmd fields containing \r, \n, semicolons, or shell metacharacters
Child processes spawned by the Nginx-UI service that do not match legitimate Nginx binaries (nginx -t, nginx -s reload)
Outbound network connections initiated by the Nginx-UI process to unfamiliar hosts
New user accounts, SSH keys, or scheduled tasks created on hosts running Nginx-UI

Detection Strategies

Inspect Nginx-UI configuration change events for CRLF byte sequences in command-related fields
Alert on process ancestry where Nginx-UI spawns shells (sh, bash) or interpreters (python, perl, curl, wget)
Correlate authenticated Nginx-UI API activity with subsequent unusual process execution on the host

Monitoring Recommendations

Enable and centralize Nginx-UI audit logs to capture configuration mutation events
Forward host process telemetry to a centralized analytics platform for behavioral correlation
Track privileged access to the Nginx-UI web interface, including source IP, session duration, and configuration endpoints touched

How to Mitigate CVE-2024-23828

Immediate Actions Required

Upgrade Nginx-UI to version 2.0.0.beta.12 or later on all affected hosts
Rotate credentials for all Nginx-UI accounts, especially any account with configuration modification privileges
Review current values of test_config_cmd and start_cmd for evidence of injected payloads and reset them to known-good defaults
Audit hosts running Nginx-UI for unauthorized processes, persistence mechanisms, or outbound connections

Patch Information

The maintainers of Nginx-UI released the fix in version 2.0.0.beta.12. The patch adds proper neutralization of CRLF characters in the affected configuration fields. Details are documented in the GitHub Security Advisory GHSA-qcjq-7f7v-pvc8.

Workarounds

Restrict network access to the Nginx-UI management interface using firewall rules, VPN, or a bastion host
Enforce strong, unique credentials and multi-factor authentication for all Nginx-UI accounts
Limit the number of principals granted permission to modify Nginx-UI configuration settings
Run Nginx-UI as a least-privileged system user to reduce the blast radius of command execution

bash

# Configuration example: restrict access to the Nginx-UI management port
# Example iptables rule allowing only a trusted management subnet
iptables -A INPUT -p tcp --dport 9000 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 9000 -j DROP

# Verify the running Nginx-UI version after upgrade
nginx-ui -v