CVE-2016-10009 in macOS
Summary
by MITRE
Untrusted search path vulnerability in ssh-agent.c in ssh-agent in OpenSSH before 7.4 allows remote attackers to execute arbitrary local PKCS#11 modules by leveraging control over a forwarded agent-socket.
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Analysis
by VulDB Data Team • 05/30/2026
The vulnerability described in CVE-2016-10009 represents a significant security flaw in the OpenSSH implementation that affects the ssh-agent component. This untrusted search path vulnerability exists in the ssh-agent.c file within OpenSSH versions prior to 7.4, creating a pathway for remote attackers to potentially execute arbitrary local PKCS#11 modules through manipulation of forwarded agent sockets. The flaw stems from improper handling of the search path when loading PKCS#11 modules, which can be exploited when users forward their SSH agent sockets to remote systems.
The technical exploitation of this vulnerability relies on the ability of a remote attacker to control or manipulate the environment in which the ssh-agent operates when agent forwarding is enabled. When users connect to remote systems with agent forwarding enabled, the ssh-agent creates a socket that can be accessed by the remote system. The vulnerability occurs because the ssh-agent does not properly validate or sanitize the search paths used to locate PKCS#11 modules, allowing an attacker to place malicious modules in directories that are searched before legitimate ones. This creates a classic privilege escalation scenario where a remote attacker can influence the loading of cryptographic modules through the forwarded agent socket, potentially executing arbitrary code with the privileges of the local user.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential privilege escalation and credential compromise. Attackers can leverage this flaw to execute malicious PKCS#11 modules that may be designed to steal cryptographic keys, monitor authentication processes, or provide backdoor access to the compromised system. The vulnerability is particularly dangerous because it can be exploited without requiring direct access to the local system, making it a significant concern for organizations that rely heavily on SSH agent forwarding for their security infrastructure. The attack vector is particularly relevant in environments where users frequently connect to remote systems and have agent forwarding enabled, as this creates the necessary conditions for exploitation.
This vulnerability aligns with CWE-427 Uncontrolled Search Path in the Common Weakness Enumeration catalog, which specifically addresses the issue of uncontrolled search paths that can lead to arbitrary code execution through module loading. The flaw also relates to ATT&CK technique T1552.001 for Unsecured Credentials and T1059.001 for Command and Scripting Interpreter, as it enables attackers to execute code through compromised agent forwarding mechanisms. Organizations should prioritize updating their OpenSSH implementations to version 7.4 or later to mitigate this risk, as the fix addresses the core issue of improper search path handling in the ssh-agent component. Additionally, administrators should review their SSH configurations to ensure that agent forwarding is not enabled in environments where it is not strictly required, and implement monitoring solutions to detect suspicious agent socket activity. The vulnerability serves as a reminder of the critical importance of proper input validation and secure coding practices in cryptographic software components that handle sensitive authentication mechanisms.