CVE-2026-106588 in OpenSSH
Summary
by MITRE • 10/07/2026
In sshd in OpenSSH through 10.6, use of the macOS 27 (or later) SDK has the side effect of loss of sandboxing, which is potentially unexpected.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified in OpenSSH versions up to and including 10.6 involves a critical regression in security posture on Apple operating systems resulting from the integration of macOS SDK version 27 or later into the build process. This issue manifests as an unintended loss of sandboxing capabilities for the sshd daemon, which is the server-side component responsible for handling incoming Secure Shell connections. The root cause lies in how newer versions of the macOS Software Development Kit interact with system-level security frameworks and entitlements during compilation and linking phases. When OpenSSH is compiled against these updated SDK headers and libraries, it inadvertently bypasses or fails to properly inherit the restrictive sandbox profiles that are typically enforced by default on modern macOS environments. This side effect suggests a misalignment between the application's expected privilege boundaries and the actual permissions granted at runtime due to changes in how system APIs interpret security contexts within newer OS versions.
From a technical perspective, this flaw represents a significant deviation from the principle of least privilege. Sandboxing is designed to limit the damage that can be done by a compromised process by restricting its access to sensitive resources such as file systems, network interfaces, and other processes. By losing these restrictions, sshd gains broader system access than intended, effectively operating with elevated privileges relative to its original security context. This environment allows an attacker who exploits any secondary vulnerability within the SSH daemon or successfully authenticates through weak credentials to perform actions that would otherwise be blocked by the sandbox. The impact extends beyond simple data exfiltration; it enables potential lateral movement across the system, modification of critical configuration files, and installation of persistent backdoors without triggering standard security alerts associated with privilege escalation attempts.
The operational impact of this vulnerability is severe for organizations relying on OpenSSH for remote administration over untrusted networks. An adversary leveraging this lack of sandboxing can escalate their access from a restricted user context to one that interacts more freely with the host operating system's core components. This increases the attack surface significantly, as many mitigations and monitoring tools rely on process isolation to detect anomalous behavior. Without these boundaries, malicious activities may blend in with legitimate administrative tasks, making detection through behavioral analysis considerably more difficult. Furthermore, this flaw undermines trust in the integrity of remote access services, forcing administrators to reconsider deployment strategies or apply immediate compensating controls until a patched version is available.
To mitigate this risk, system administrators should immediately verify whether their OpenSSH installations were compiled using macOS SDK 27 or later and assess if sandboxing restrictions are active for sshd processes. If the vulnerability is confirmed, applying vendor-provided patches that restore proper entitlement inheritance is the primary remediation step. In cases where patching is not immediately feasible, implementing strict firewall rules to limit SSH access to trusted IP addresses only can reduce exposure. Additionally, deploying host-based intrusion detection systems configured to monitor for unusual file system modifications or network connections originating from sshd processes provides an additional layer of defense. Organizations should also review their security policies regarding remote authentication mechanisms, ensuring that key-based authentication is enforced and password authentication is disabled where possible to minimize the risk of unauthorized access exploiting this broader permission set.
This issue aligns with CWE-250, which describes execution with unnecessary privileges, as the process operates outside its intended confinement boundaries. It also relates to CWE-693, Protection Mechanism Failure, specifically regarding the failure of a security mechanism (sandboxing) to protect against attacks that it was designed to prevent. In terms of MITRE ATT&CK framework tactics, this vulnerability facilitates Privilege Escalation and Defense Evasion techniques by allowing an attacker to operate within a less monitored and more permissive environment than originally configured. Understanding these mappings helps in categorizing the severity correctly and prioritizing remediation efforts based on established industry standards for vulnerability management and security hardening practices.