CVE-2016-10011 in macOS
Summary
by MITRE
authfile.c in sshd in OpenSSH before 7.4 does not properly consider the effects of realloc on buffer contents, which might allow local users to obtain sensitive private-key information by leveraging access to a privilege-separated child process.
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Analysis
by VulDB Data Team • 05/30/2026
The vulnerability identified as CVE-2016-10011 resides within the OpenSSH implementation's sshd daemon, specifically in the authfile.c component that handles authentication file processing. This flaw manifests in versions of OpenSSH prior to 7.4 and represents a critical security issue that could potentially expose sensitive private key information to local attackers. The vulnerability occurs within the privilege separation mechanism that OpenSSH employs to isolate critical operations from the main daemon process, creating a unique attack surface that leverages the interaction between memory management functions and authentication handling.
The technical root cause of this vulnerability stems from improper handling of memory reallocation within the authentication file processing code. When sshd processes authentication files and encounters situations requiring buffer expansion, the realloc function may not properly preserve the contents of the original buffer during memory reallocation operations. This memory management flaw becomes particularly dangerous within the privilege-separated child process context where authentication operations occur. The realloc function's behavior when moving memory blocks can result in sensitive data remaining in memory locations that are subsequently reused or accessed by other processes, creating potential information leakage scenarios.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables local users to potentially extract private key material that should remain protected within the privilege-separated child process. Attackers who gain access to this child process can exploit the flawed memory handling to read sensitive data from memory locations that were previously occupied by authentication information. This represents a significant compromise of the privilege separation model that OpenSSH employs as a security boundary, allowing attackers to bypass the intended isolation between the privileged parent process and unprivileged child processes. The vulnerability specifically affects the handling of private key information that may be temporarily stored in buffers during authentication processing, potentially exposing cryptographic material that could be used for further attacks or unauthorized access.
Mitigation strategies for CVE-2016-10011 primarily focus on upgrading to OpenSSH version 7.4 or later, which includes the necessary patches to address the memory management issues in authfile.c. Organizations should prioritize immediate deployment of the updated OpenSSH packages to eliminate this vulnerability from their systems. Additionally, system administrators should conduct thorough security audits to identify any systems running vulnerable versions of OpenSSH and ensure proper patch management procedures are in place. The vulnerability aligns with CWE-129, which addresses improper handling of memory reallocations, and relates to ATT&CK technique T1552.001 for unsecured credentials and T1068 for exploit for privilege escalation. Security monitoring should be enhanced to detect unusual memory access patterns and privilege separation anomalies that might indicate exploitation attempts. Regular vulnerability assessments should include checks for OpenSSH installations to prevent similar memory management issues from affecting system security posture.