CVE-2025-14946 in libnbd
Summary
by MITRE • 12/19/2025
A flaw was found in libnbd. A malicious actor could exploit this by convincing libnbd to open a specially crafted Uniform Resource Identifier (URI). This vulnerability arises because non-standard hostnames starting with '-o' are incorrectly interpreted as arguments to the Secure Shell (SSH) process, rather than as hostnames. This could lead to arbitrary code execution with the privileges of the user running libnbd.
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Analysis
by VulDB Data Team • 12/20/2025
The vulnerability identified as CVE-2025-14946 resides within the libnbd library, a critical component used for network block device operations in virtualization environments. This flaw represents a classic command injection vulnerability that exploits improper input validation and argument parsing mechanisms. The issue manifests when libnbd processes URIs containing non-standard hostnames that begin with the '-o' prefix, which is typically used to denote SSH options in command-line interfaces. The root cause of this vulnerability can be categorized under CWE-78 as a command injection flaw, where user-supplied input is improperly handled and executed as part of a command. When a malicious actor crafts a URI with a hostname starting with '-o', the library fails to properly sanitize this input, leading to unintended interpretation of the string as command-line arguments rather than legitimate host identifiers.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass full arbitrary code execution capabilities within the context of the user running libnbd. This presents a significant risk in environments where libnbd operates with elevated privileges or in automated systems where untrusted URI inputs may be processed. The vulnerability creates an attack surface where remote adversaries can manipulate the SSH connection process by injecting malicious SSH options through the hostname field. This type of flaw aligns with ATT&CK technique T1059.001 for command and scripting interpreter, specifically targeting the execution of commands through SSH protocols. The exploitation chain typically involves crafting a malicious URI that includes '-o' prefixed options such as '-o ProxyCommand' or similar SSH directives that can redirect execution flow or inject commands into the SSH process.
The technical exploitation of this vulnerability requires understanding the underlying SSH argument parsing behavior and how libnbd integrates with SSH for remote connections. When libnbd encounters a URI with a hostname starting with '-o', it incorrectly treats this as a sequence of SSH options rather than a literal hostname, allowing for injection of arbitrary SSH configuration directives. This misinterpretation creates a path where attackers can leverage the SSH connection mechanism to execute code on the target system, potentially escalating privileges based on the user context in which libnbd operates. The vulnerability demonstrates a fundamental flaw in input validation and parameter handling that violates secure coding principles and best practices for preventing injection attacks. Organizations utilizing libnbd in virtualization stacks, cloud environments, or automated infrastructure management systems face particular risk, as these environments often process untrusted URI inputs from multiple sources. The impact is amplified in scenarios where libnbd runs with administrative privileges or in containerized environments where privilege escalation could lead to broader system compromise. Mitigation strategies must focus on input sanitization, proper URI parsing, and ensuring that all user-supplied data is properly escaped or validated before being passed to underlying SSH processes. The vulnerability also highlights the importance of implementing proper security controls around network block device operations and ensuring that all external inputs are treated as potentially malicious until proven otherwise.