CVE-2018-8779 in macOS
Summary
by MITRE
In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, the UNIXServer.open and UNIXSocket.open methods are not checked for null characters. It may be connected to an unintended socket.
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Analysis
by VulDB Data Team • 05/10/2026
The vulnerability described in CVE-2018-8779 represents a critical security flaw in Ruby's handling of UNIX domain socket connections that affects multiple versions of the Ruby programming language. This issue stems from insufficient input validation in the UNIXServer.open and UNIXSocket.open methods, which fail to properly sanitize or reject null character inputs that could be used to manipulate socket connections. The vulnerability falls under the category of improper input validation and can be classified as CWE-770, which deals with allocation of resources without limits or throttling. The flaw enables attackers to potentially establish connections to unintended socket endpoints by exploiting the lack of null character checks during socket creation operations.
The technical implementation of this vulnerability occurs when Ruby applications attempt to create UNIX domain sockets using the open methods without proper validation of the socket path parameter. When a null character is present within the socket path string, the underlying system may interpret the string differently than intended, potentially allowing an attacker to redirect socket connections to alternative locations. This behavior can be exploited in scenarios where applications create sockets based on user input or untrusted data sources, creating opportunities for unauthorized access or connection manipulation. The vulnerability specifically affects Ruby versions prior to 2.2.10, 2.3.7, 2.4.4, 2.5.1, and 2.6.0-preview1, indicating a widespread impact across multiple Ruby release lines.
The operational impact of CVE-2018-8779 extends beyond simple socket manipulation to potentially enable more severe security consequences. Attackers could leverage this vulnerability to perform unauthorized connections to system services, intercept communications, or gain access to restricted resources that should only be accessible through legitimate socket endpoints. The vulnerability aligns with ATT&CK technique T1071.004 for application layer protocol usage and can be categorized under the broader category of privilege escalation or lateral movement attacks. Organizations running Ruby applications that create UNIX domain sockets based on external input may be at risk of unauthorized access to system resources, potentially leading to data breaches or system compromise.
Mitigation strategies for this vulnerability require immediate patching of affected Ruby versions to the latest stable releases that contain the necessary input validation fixes. System administrators should also implement proper input sanitization within applications that utilize UNIX socket operations, particularly when dealing with user-provided data. The recommended approach includes validating all socket path parameters for null characters and other potentially malicious input patterns before attempting socket creation. Organizations should also consider implementing network segmentation and access controls to limit potential impact if exploitation occurs. Additional defensive measures include monitoring for unusual socket connection patterns and implementing proper application security testing that includes input validation checks for all socket-related operations. The vulnerability demonstrates the importance of proper input validation in system-level operations and highlights the need for comprehensive security testing across all application components that interact with system resources.