External risk intelligence

IODD File Upload Allows Root Shell Script Execution.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-27565

The vulnerability involves the processing of IODD (IO Device Description) files, which are commonly used in industrial automation and remote management interfaces. As these systems are often exposed via web-based management portals or gateways to facilitate remote device monitoring and configuration, they are frequently reachable from the internet in typical deployments.

OS Command Injection

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability allows unauthenticated attackers to execute commands with full system privileges by uploading a malicious file. This could potentially lead to unauthorized control and persistent access on affected systems, even after reboots. The main concern is confirming relevance and exposure.

Attackers can run commands with root access.
Persistent access after reboot is a key risk.
Confirm if our systems are susceptible.

Attack Path

How an attacker could exploit the issue

An attacker can remotely upload a malicious file to a system. This file, when processed, allows an attacker to execute a shell script with the highest level of system control. The script continues to run even if the system restarts, posing a persistent threat.

No authentication required for access.
Malicious file upload and processing.
Persistent root-level code execution.

Live Threat

Current exploitation, exposure, and threat context

An unauthenticated remote attacker could upload a malicious file, leading to the execution of a persistent shell script with root privileges. This could affect system integrity and availability by allowing unauthorized commands to run even after a reboot.

System data and control could be compromised.
Malicious file upload and execution.
Root-level persistent unauthorized access.

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability requires immediate attention from teams responsible for industrial control systems and network-accessible devices. The initial focus should be on identifying all instances of the affected technology, assessing their exposure and business criticality, and confirming the accountable system owner. Once identified, a risk-based remediation plan, potentially involving vendor coordination or temporary mitigations, should be developed.

Identify and confirm system owners.
Verify external reachability and criticality.
Plan remediation with vendor coordination.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is an IODD file used for in industrial systems?

IODD stands for IO Device Description. These files are standard configuration documents that help automation systems, like IO-Link masters, identify and communicate with connected sensors and actuators. They essentially act as digital manuals that allow a management portal or gateway to correctly interpret data and configure device settings for industrial control.

What does CWE-78 mean regarding CVE-2026-27565?

CWE-78 refers to Improper Neutralization of Special Elements used in an OS Command. In plain English, the software fails to properly check or sanitize the IODD file before processing it. Because the system treats the file input as a command to be run, an attacker can insert their own instructions. This allows them to bypass security controls and execute unauthorized code directly on the underlying operating system.

How does an attacker trigger this vulnerability?

An attacker triggers this by uploading a specially crafted, malicious IODD file to the system. The flaw exists because the software processes this file without requiring any user authentication. It is important to note that the vulnerability is specifically tied to the processing of the file itself; simply accessing the management portal without successfully performing an unauthorized upload does not trigger the execution of the shell script.

Why is Halo Surface Signal labeling this CVE as likely to be exposed?

Halo Surface Signal identifies this as a potential risk because IODD files are often handled by web-based management portals and gateways. These interfaces are frequently placed on internet-facing networks to enable remote monitoring and device configuration. Because these systems are designed to be reachable for remote management, they often lack the network-level restrictions that would otherwise prevent an external attacker from reaching the upload function.

What are the first steps to address this issue?

Begin by creating an inventory of all devices in your environment that process IODD files. Once you have identified these systems, determine which ones are accessible from outside your local network. Confirm the ownership of these devices and coordinate with the equipment vendor to obtain official guidance or security updates. Prioritize high-criticality assets that serve as the primary gateway for your industrial operations.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.