CVE-2026-83923 in Windows
Summary
by MITRE • 10/14/2026
Relative path traversal in OpenSSH for Windows allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a relative path traversal flaw within the implementation of OpenSSH for Windows, which can be exploited by an unauthenticated or low-privileged remote attacker to achieve arbitrary code execution on the target system. This type of security defect typically arises when software constructs file paths using user-supplied input without adequately validating that the resulting path remains confined within a designated secure directory structure. In the context of OpenSSH for Windows, this flaw likely affects components responsible for handling file operations during authentication or session management processes, such as subsystem execution or key-based login mechanisms where file system interactions are necessary. By manipulating relative paths through specially crafted network requests, an attacker can direct the application to access and execute files located outside the intended sandboxed environment, potentially reaching sensitive areas of the operating system or executing malicious payloads with the privileges associated with the SSH service process.
From a technical perspective, this vulnerability aligns closely with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, which is categorized under CWE Category 1003: Weaknesses in Access Control. The core issue lies in the failure to canonicalize or strictly validate path components before processing them, allowing sequences such as dot-dot-slash (../) to escape the expected directory boundaries. This lack of rigorous input sanitization enables an attacker to bypass access controls that are designed to restrict file operations to specific directories. When combined with the high-privilege nature of many SSH daemon processes on Windows systems, which often run under SYSTEM or Administrator accounts depending on configuration, the ability to traverse paths and execute code can lead to a complete compromise of the host machine. The operational impact is severe, as it allows for remote code execution without prior authentication in some configurations, effectively granting an attacker full control over the affected system.
In terms of threat modeling and adversary behavior, this vulnerability maps directly to MITRE ATT&CK technique T1059: Command and Scripting Interpreter, specifically under sub-techniques involving Windows command shell or PowerShell if the execution vector allows for script interpretation. Furthermore, it relates to T1203: Exploitation for Client Execution if the attack involves client-side components, though given the server context of OpenSSH, it is more accurately described as a remote exploitation leading to initial access and privilege escalation. The attacker can leverage this flaw to establish persistence, move laterally within a network by exploiting other systems running vulnerable versions, or exfiltrate data from directories that were previously considered secure due to their location outside the SSH root directory.
Mitigation strategies for this vulnerability primarily involve applying vendor-provided patches that address the path validation logic in the affected OpenSSH binaries. Organizations should ensure that all instances of OpenSSH for Windows are updated to versions where the relative path traversal issue has been resolved through improved input sanitization and strict boundary enforcement. Additionally, defense-in-depth measures such as running the SSH service under a least-privilege account rather than SYSTEM can significantly reduce the impact if exploitation occurs. Network-level controls like firewalls should be configured to restrict access to port 22 only from trusted IP ranges, thereby limiting the attack surface available to remote attackers attempting to exploit this flaw. Regular vulnerability scanning and monitoring for anomalous file system activity related to SSH processes are also recommended to detect potential exploitation attempts in real-time.