CVE-2026-67986 in amazing_print
Summary
by MITRE • 08/13/2026
amazing-print/amazing_print at commit dc890dfafdf07088ea901df53c19c2710e5c5234 contains a Ruby code injection condition in AwesomeMethodArray#grep. A specially named method containing Ruby interpolation syntax can be interpolated into a dynamically constructed eval string when grep is called with a block, resulting in Ruby code execution in the host process. Exploitation requires an application path that allows an attacker to influence dynamic method names.
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Analysis
by VulDB Data Team • 08/13/2026
The vulnerability exists within the amazing-print gem version at commit dc890dfafdf07088ea901df53c19c2710e5c5234 where the AwesomeMethodArray#grep method contains a critical Ruby code injection flaw. This security issue arises from improper handling of dynamically constructed eval strings when the grep method is invoked with a block parameter. The flaw specifically occurs when method names containing Ruby interpolation syntax are processed through the dynamic evaluation mechanism, allowing attackers to inject arbitrary Ruby code that executes within the context of the host process. The vulnerability represents a classic code injection weakness that can be leveraged to execute malicious commands remotely or locally depending on the application's trust model and execution environment.
The technical implementation of this vulnerability stems from the improper sanitization of method names within the AwesomeMethodArray#grep method. When a block is provided to grep, the system constructs an eval string that incorporates method names directly into the dynamic code execution flow without adequate input validation or escaping mechanisms. This creates a condition where attacker-controlled method names containing interpolation syntax such as #{...} can be processed and evaluated as Ruby code. The CWE-94 weakness classification applies here as this represents an improper neutralization of special elements used in code execution contexts, specifically through the use of eval with unsanitized input. The attack vector requires that an application path exists where an attacker can influence or control method names that are subsequently processed by this vulnerable method.
The operational impact of this vulnerability extends beyond simple code injection to potentially enable full system compromise when exploited correctly. An attacker who can manipulate method names through input parameters or other attack vectors can execute arbitrary Ruby code with the privileges of the hosting process, which could include access to sensitive data, file system operations, network communications, or even privilege escalation in some environments. The vulnerability affects applications that utilize the amazing-print gem and specifically those that allow user-controlled method names to flow into the grep method with block parameters. This creates a significant risk for web applications, API endpoints, or any system where user input might influence dynamic method creation or naming within the gem's processing pipeline.
Mitigation strategies should focus on immediate remediation through updating to a patched version of the amazing-print gem where the vulnerable eval operations have been replaced with safe alternatives that properly sanitize input before code execution. Organizations should also implement input validation and sanitization measures at application boundaries to prevent attacker-controlled method names from reaching the vulnerable code path. The ATT&CK framework's T1059.007 technique for "Ruby" scripting languages applies here as this vulnerability enables an attacker to execute Ruby commands through the injection mechanism. Additionally, defensive measures should include runtime monitoring for suspicious eval operations and implementing least privilege principles to limit the impact of successful exploitation attempts, ensuring that even if exploitation occurs, the attacker's capabilities remain constrained within the system's security boundaries.