CVE-2024-9441

What it actually does

This is a remote, unauthenticated OS command injection vulnerability in Linear eMerge e3-Series access control systems through version 1.00-07. The forgot password workflow accepts a login_id parameter over HTTP and fails to safely validate or escape it before using it in an operating system command. An attacker can place shell metacharacters or command syntax in login_id and cause the appliance to execute arbitrary commands with the privileges of the affected service. Successful exploitation can allow full compromise of the device, including reading sensitive data, modifying configuration, installing malware, disabling services, or using the system as a foothold into adjacent networks.

Why it matters to the business

Because eMerge systems are commonly used for physical access control, compromise can affect both cyber operations and facility security. An attacker could disrupt door control operations, alter access configurations, harvest credentials or user data, implant persistent malware, or use the device to pivot into other internal systems. The vulnerability is network-exploitable without authentication, has a critical CVSS score, and has a high EPSS probability, so internet-exposed or broadly reachable management interfaces should be treated as high-priority risks even though it is not currently listed in CISA KEV.

How an attack unfolds

An attacker first identifies a reachable Linear eMerge e3-Series web interface, typically by scanning for exposed HTTP services or known device fingerprints. The attacker then sends an HTTP request to the forgot password functionality and places shell command syntax in the login_id parameter. Because the application passes that value into an operating system command without proper sanitization, the injected command is executed on the appliance. The attacker may begin with a harmless reconnaissance command such as whoami, id, uname, or network checks, then progress to downloading tooling, opening a reverse shell, modifying configuration, creating persistence, or disrupting access-control services. If the device has access to internal networks, the compromised appliance can also be used as a pivot point for further reconnaissance and lateral movement.

How to fix it

Upgrade Linear eMerge e3-Series devices to a vendor-supported release that fixes this issue; systems running version 1.00-07 or earlier should be considered affected. If an exact fixed version is not available from asset records, obtain current firmware and remediation instructions directly from the vendor or authorized support channel. Until patched, remove the management web interface from the internet, restrict HTTP/HTTPS access to a dedicated management network or VPN, block untrusted access to the forgot password functionality where feasible, and enforce network ACLs so only administrative workstations can reach the appliance. Disable or firewall outbound internet access from the device except to explicitly required destinations. If patching is unavailable, prioritize compensating controls, replacement, or isolation because unauthenticated command execution on an access-control appliance is a high-impact condition.

How to confirm the fix worked

Confirm exposure by inventorying Linear eMerge e3-Series appliances and verifying firmware versions; any device at or below 1.00-07 should be treated as vulnerable unless the vendor confirms otherwise. Validate remediation by confirming the installed firmware is newer than the affected release or explicitly documented as fixed by the vendor. From an authorized test system, verify that unauthenticated requests to the forgot password function no longer allow shell metacharacters in login_id to affect server behavior; use only benign validation such as blocked-input checks, HTTP error behavior, or controlled out-of-band DNS/timing tests approved by the organization. Also verify that the web management interface is not reachable from untrusted networks and that firewall rules restrict access to approved administrative sources only.

Typical attack path

1. Scan for internet-exposed or internally reachable Linear eMerge e3-Series HTTP interfaces.
2. Confirm the target is running an affected version through banners, web UI behavior, fingerprints, or device metadata.
3. Send a crafted forgot password HTTP request with command syntax embedded in the login_id parameter.
4. Use command output, timing behavior, or outbound callbacks to confirm command execution.
5. Run reconnaissance commands to identify privileges, firmware, network interfaces, users, and reachable internal systems.
6. Download or stage additional payloads using tools such as wget, curl, tftp, busybox, or shell redirection if available.
7. Establish persistence, modify device configuration, harvest data, disrupt access-control functions, or pivot into adjacent systems.

How to detect it

Review web server, reverse proxy, WAF, firewall, IDS, and packet-capture logs for HTTP requests to the forgot password function containing login_id values with shell metacharacters such as semicolons, pipes, ampersands, backticks, dollar-parentheses, redirection operators, or URL-encoded equivalents. Look for command names commonly used after injection, including whoami, id, uname, cat, echo, wget, curl, tftp, busybox, nc, netcat, sh, bash, chmod, and rm. Because embedded access-control devices may have limited local logging, correlate network telemetry for unexpected outbound DNS, HTTP, HTTPS, TFTP, or TCP sessions originating from the appliance shortly after forgot password requests. Investigate configuration changes, new or modified users, altered access schedules, unexpected reboots, disabled services, modified startup scripts, unknown files in writable temporary locations, and deviations from the known-good firmware or configuration baseline. If the appliance manages physical access, also review access-control audit events around the suspected exploitation window for unusual unlocks, credential changes, schedule changes, or administrative actions.

• forgot_password
• login_id=
• login_id=%3B
• login_id=%7C
• login_id=%26
• login_id=%60
• login_id=$(
• login_id=%24%28
• login_id=;
• login_id=|
• login_id=&
• login_id=`
• login_id=>
• login_id=%3E
• login_id=%0A
• login_id=%0D
• whoami
• uname -a
• /bin/sh
• /bin/bash
• busybox
• wget http
• curl http
• tftp -g
• nc -e
• netcat -e
• chmod +x
• /tmp/
• /var/tmp/

What your security team should do

• Immediately identify all Linear eMerge e3-Series appliances and determine whether any are running version 1.00-07 or earlier.
• Prioritize remediation for internet-facing devices and devices reachable from user networks, guest networks, building networks, or third-party remote access paths.
• Upgrade to a vendor-supported fixed firmware release or replace unsupported devices.
• Restrict management web access to a dedicated administrative network or VPN and block direct internet exposure.
• Review recent HTTP requests to forgot password functionality for login_id values containing shell metacharacters, URL-encoded command separators, or suspicious command names.
• Inspect network telemetry for unexpected outbound connections from access-control appliances, especially HTTP, DNS, TFTP, or reverse-shell-like traffic to unfamiliar destinations.
• If exploitation is suspected, preserve logs and device images where possible, rotate credentials associated with the appliance, review access-control configuration changes, and consider rebuilding or replacing the device from trusted firmware.
• Add compensating detections in WAF, IDS, proxy, and SIEM tooling for command-injection patterns targeting forgot_password and login_id parameters.