External risk intelligence

Image Optimizer Ruby Gem OS Command Injection

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-107704

The vulnerability exists in a Ruby gem used for image optimization. This functionality is commonly integrated into public-facing web applications that process user-uploaded files, such as profile pictures or content management systems. Because the application logic often passes user-controlled filenames directly to this gem, it frequently results in an externally reachable attack surface in web 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 vulnerability has been identified in the image_optimizer Ruby gem, which could allow attackers to execute commands on systems that use it for image processing. This occurs when processing specially crafted image file paths, potentially leading to unauthorized command execution with the privileges of the Ruby process.

Attackers can run commands by exploiting image processing.
This gem is used in web apps processing user uploads.
Assess if your systems use this gem for image handling.

Attack Path

How an attacker could exploit the issue

Attackers can trigger this vulnerability by submitting a specially crafted image file name to an application that uses the image_optimizer Ruby gem. When the application processes this input, an attacker-controlled path can be used to inject operating system commands that execute with the privileges of the Ruby process.

Attacker controls image path.
Vulnerable `identify_format` function.
Arbitrary command execution.

Live Threat

Current exploitation, exposure, and threat context

When the `identify` option is enabled, attackers could execute commands on the server by supplying a crafted image path. This could lead to the execution of arbitrary commands with the privileges of the Ruby process.

Server-side code execution.
User-controlled input execution.
System compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

The `image_optimizer` Ruby gem is susceptible to OS command injection, posing a critical risk. Application owners and platform teams are likely responsible for addressing this vulnerability, as it affects how their applications handle image processing, potentially involving user-controlled input. The immediate priority is to identify all instances of the affected gem within the environment and assess their exposure.

App owners and platform teams responsible.
Verify gem usage and file path handling.
Plan coordinated updates or mitigating controls.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is the image_optimizer Ruby gem?

The image_optimizer gem is a software library for the Ruby programming language used to compress and manage image files. Developers typically integrate this component into web applications to automatically process images uploaded by users, such as profile avatars, product photos, or media galleries, ensuring they are optimized for performance.

How does CVE-2026-107704 work?

This vulnerability is an OS command injection flaw, categorized as CWE-78. It happens because the gem fails to properly sanitize input when identifying image formats. If the `identify` option is enabled, the code uses user-provided file paths directly in system commands. An attacker can insert shell metacharacters into the path to trick the Ruby process into executing unauthorized system-level commands.

What triggers this command injection vulnerability?

The flaw is triggered when an application passes a malicious, attacker-controlled file path to the gem's `identify_format` function. Simply using the gem in your project is not enough to trigger it; the vulnerability remains inactive if the application logic does not use the specific `identify` option or if the file path inputs are strictly validated and sanitized before they reach the gem's processing functions.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal indicates that this vulnerability is likely to be exposed in public-facing web applications. Because this gem is frequently used to handle user-uploaded files, any application that allows users to submit or rename files via an internet-facing interface is at higher risk. Internal systems that do not process external user input face a lower immediate risk.

How do I start responding to this threat?

Begin by auditing your codebase to locate where the image_optimizer gem is utilized. Identify every place in your application logic that passes external input, such as file names, into the gem's processing functions. Once identified, evaluate whether the `identify` feature is strictly necessary and prioritize updating the gem or applying robust input validation to prevent unauthorized characters from reaching the system command shell.

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.