CVE-2026-12545 in hammer_cli
Summary
by MITRE • 10/01/2026
A flaw was found in rubygem-hammer_cli. A command injection vulnerability exists in Hammer CLI and the Railties (Ruby on Rails) component distributed with Satellite due to the insecure interpolation of the $EDITOR environment variable into the Ruby system() method. By passing a single interpolated string to system(), the application invokes a system shell (/bin/sh) that interprets shell metacharacters (e.g., ;, |, &).
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified in rubygem-hammer_cli represents a critical command injection flaw rooted in insecure handling of environment variables within Ruby on Rails applications. Specifically, the Railties component distributed with Red Hat Satellite improperly interpolates the $EDITOR environment variable directly into calls to the Ruby system() method. This architectural decision creates a direct pathway for attackers to execute arbitrary operating system commands because the application fails to sanitize or validate user-supplied input before passing it to the underlying shell interpreter. The core technical flaw lies in the use of single-string interpolation, which causes the Ruby runtime to invoke /bin/sh and interpret any embedded shell metacharacters such as semicolons, pipes, ampersands, and backticks. This behavior effectively bypasses intended security controls by allowing an attacker to chain multiple commands or redirect output within the context of the vulnerable application process.
From a technical perspective, this vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The severity is exacerbated because environment variables like EDITOR are often influenced by user configuration and can be manipulated through various vectors including crafted HTTP requests or local file modifications if the attacker has any level of access to the system running the application. When a single interpolated string containing malicious shell syntax is passed to the system() method, the operating system's command interpreter processes these characters as executable instructions rather than literal data. This allows for remote code execution with the privileges assigned to the service account running Hammer CLI or Satellite components, potentially leading full compromise of the underlying infrastructure if proper isolation measures are not in place.
The operational impact of this vulnerability is severe, enabling unauthorized access and control over critical satellite management functions. An authenticated attacker could exploit this flaw to read sensitive configuration files, exfiltrate database contents by piping output to external services, or install persistent backdoors on the server hosting Satellite. In enterprise environments where Red Hat Satellite manages large fleets of systems, compromising the management node can provide a foothold for lateral movement across the network. The ability to execute arbitrary commands means that attackers could disable security monitoring tools, modify system configurations, or pivot to other connected infrastructure components, thereby undermining the integrity and availability of the entire managed environment.
Mitigation strategies must focus on immediate remediation through vendor-provided patches as well as defensive coding practices for any custom integrations involving Hammer CLI. Organizations should apply the latest updates released by Red Hat which address this specific interpolation issue in both hammer_cli and Railties components. In environments where patching is not immediately feasible, administrators can implement strict input validation to ensure that only expected alphanumeric characters are accepted when interacting with editor-related functionalities. Additionally, restricting the EDITOR environment variable to safe, non-executable paths or disabling its use entirely for automated processes can reduce the attack surface. Security teams should also monitor system logs for unusual shell activity originating from Satellite service accounts and enforce least-privilege principles so that even if exploitation occurs, the potential damage is contained within a restricted permission set aligned with industry standards such as MITRE ATT&CK techniques related to command and script interpretation.