CVE-2007-0726 in Mac OS X
Summary
by MITRE
The SSH key generation process in OpenSSH in Apple Mac OS X 10.3.9 and 10.4 through 10.4.8 allows remote attackers to cause a denial of service by connecting to the server before SSH has finished creating keys, which causes the keys to be regenerated and can break trust relationships that were based on the original keys.
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Analysis
by VulDB Data Team • 06/14/2025
The vulnerability identified as CVE-2007-0726 represents a significant flaw in the Secure Shell key generation mechanism within OpenSSH implementations on Apple Mac OS X systems. This issue specifically affects versions 10.3.9 and 10.4 through 10.4.8, where the timing of SSH key creation creates a window of opportunity for malicious actors to exploit the system's key generation process. The flaw stems from the asynchronous nature of key generation during system boot or service restart, where the SSH daemon may not have completed key creation when remote connections attempt to establish trust relationships.
The technical implementation of this vulnerability exploits a race condition in the SSH key management system where remote attackers can establish connections to the SSH server before the key generation process has completed. This timing discrepancy allows attackers to force the system to regenerate SSH keys prematurely, effectively disrupting the established trust relationships between clients and the server. The vulnerability operates at the protocol level where SSH key exchange mechanisms are not properly synchronized with the availability of cryptographic keys, creating an exploitable state where key regeneration occurs under adversarial conditions rather than during normal system operations.
From an operational impact perspective, this vulnerability enables remote attackers to execute denial of service attacks against SSH services without requiring authentication or specific privileges. The consequences extend beyond simple service disruption as the key regeneration process can break existing trust relationships that other services may depend upon, potentially affecting system integrity and availability. The attack vector is particularly concerning because it can be executed remotely without prior access to the system, making it a low-effort, high-impact vulnerability that could compromise the security posture of affected systems.
The vulnerability aligns with CWE-362, which describes race conditions in security-critical operations, and demonstrates characteristics consistent with ATT&CK technique T1499.004, which involves network denial of service attacks. Organizations running affected versions of Mac OS X should implement immediate mitigations including system updates to patched versions of OpenSSH, network segmentation to limit SSH access, and monitoring for unusual SSH connection patterns. The recommended approach involves ensuring that SSH key generation completes before accepting connections and implementing proper synchronization mechanisms to prevent premature key regeneration during service startup or restart operations.