CVE-2026-27548: Command Injection RCE Vulnerability

CVE-2026-27548 Overview

CVE-2026-27548 is a command injection vulnerability [CWE-78] affecting the /index.php/ajax/get_iodd_port_info endpoint of an industrial device web interface. A low-privileged remote attacker holding user or operator credentials can inject operating system commands into the endpoint. The injected commands execute with root privileges on the underlying device.

The issue was published to the National Vulnerability Database (NVD) on 2026-09-16 and coordinated through CERT@VDE advisories VDE-2026-014, VDE-2026-027, and VDE-2026-028. The vulnerability affects confidentiality, integrity, and availability of the target device.

Critical Impact
Authenticated attackers with the lowest available role can achieve full root-level code execution on affected devices over the network.

Affected Products

Devices exposing the /index.php/ajax/get_iodd_port_info PHP endpoint covered by CERT@VDE advisory VDE-2026-014
Devices covered by CERT@VDE advisory VDE-2026-027
Devices covered by CERT@VDE advisory VDE-2026-028

Discovery Timeline

2026-09-16 - CVE-2026-27548 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-27548

Vulnerability Analysis

The vulnerability is a classic OS command injection flaw in a web-facing PHP endpoint on an embedded device. The endpoint /index.php/ajax/get_iodd_port_info accepts request parameters that are passed to an operating system shell without adequate sanitization or argument separation.

Because the web application runs with root privileges on the device, any injected shell metacharacters or additional commands are executed as root. This transforms a low-privileged authenticated session into full device compromise, including firmware modification, credential theft, and lateral movement into the operational technology (OT) network.

The CWE-78 classification indicates improper neutralization of special elements used in an OS command. Exploitation requires only user or operator credentials, which are the lowest privilege tiers on the affected platform.

Root Cause

The root cause is unsafe construction of a shell command string using untrusted input received by the get_iodd_port_info AJAX handler. Input validation and safe process-execution APIs are not applied before the command is passed to a shell interpreter, allowing metacharacters such as ;, |, &, and backticks to break out of the intended command context.

Attack Vector

An attacker first authenticates to the web interface using any valid user or operator account, including default or shared credentials common in industrial deployments. The attacker then submits a crafted HTTP request to the /index.php/ajax/get_iodd_port_info endpoint with malicious payload data in a vulnerable parameter. The server concatenates the payload into a shell command, and the injected commands execute as root.

No user interaction is required beyond the initial authentication. Refer to the CERT@VDE advisory VDE-2026-014 for endpoint-specific technical detail.

Detection Methods for CVE-2026-27548

Indicators of Compromise

HTTP POST or GET requests to /index.php/ajax/get_iodd_port_info containing shell metacharacters such as ;, |, &, $(, or backticks in parameter values
Unexpected child processes spawned by the web server process (for example, sh, bash, wget, curl, nc) running as root
New or modified files under web-writable directories, /tmp, or system binary paths on the affected device
Outbound connections initiated from the device to unfamiliar IP addresses shortly after web requests to the vulnerable endpoint

Detection Strategies

Inspect web server access logs for requests to get_iodd_port_info that include URL-encoded shell characters (%3B, %7C, %26, %24%28)
Correlate authenticated low-privilege sessions with subsequent root-level process activity on the device
Deploy network intrusion detection signatures that match command injection patterns targeting the vulnerable endpoint path

Monitoring Recommendations

Forward device web server and syslog output to a centralized logging platform for retention and correlation
Alert on any successful authentication to the device followed by anomalous outbound network traffic
Baseline normal request patterns to /index.php/ajax/ endpoints and flag deviations in parameter structure or size

How to Mitigate CVE-2026-27548

Immediate Actions Required

Restrict network access to the device management interface using firewall rules, VLAN segmentation, or a jump host, and block access from untrusted networks
Rotate all user and operator credentials on affected devices, and remove any shared or default accounts
Review web server logs for prior exploitation attempts against /index.php/ajax/get_iodd_port_info
Apply vendor firmware updates as soon as they are made available through the referenced CERT@VDE advisories

Patch Information

Refer to the vendor coordination advisories for patch availability and firmware versions: CERT@VDE Advisory VDE-2026-014, CERT@VDE Advisory VDE-2026-027, and CERT@VDE Advisory VDE-2026-028. Apply the fixed firmware version listed in each advisory that matches your device model.

Workarounds

Place the device behind a network firewall that restricts inbound HTTP/HTTPS access to a small set of trusted management workstations
Disable or remove low-privilege user and operator accounts that are not strictly required for operations
Monitor and log all web management activity, and terminate sessions from unexpected source addresses