CVE-2019-10167 in libvirtd
Summary
by MITRE
The virConnectGetDomainCapabilities() libvirt API, versions 4.x.x before 4.10.1 and 5.x.x before 5.4.1, accepts an "emulatorbin" argument to specify the program providing emulation for a domain. Since v1.2.19, libvirt will execute that program to probe the domain's capabilities. Read-only clients could specify an arbitrary path for this argument, causing libvirtd to execute a crafted executable with its own privileges.
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Analysis
by VulDB Data Team • 11/23/2025
The vulnerability identified as CVE-2019-10167 represents a critical privilege escalation flaw within the libvirt virtualization management library. This issue affects libvirt versions 4.x.x prior to 4.10.1 and 5.x.x prior to 5.4.1, where the virConnectGetDomainCapabilities() API function demonstrates insecure parameter handling that can be exploited by unauthorized users. The vulnerability stems from the library's treatment of the "emulatorbin" argument which is designed to specify the program responsible for providing emulation capabilities for virtual domains. When this argument is processed, libvirt executes the specified program to probe domain capabilities, creating an execution path that can be manipulated by malicious actors.
The technical flaw manifests in the lack of proper input validation and sanitization for the emulatorbin parameter. Specifically, read-only clients who should not have elevated privileges can manipulate this parameter to point to arbitrary executable paths. This vulnerability falls under CWE-78 Improper Neutralization of Special Elements used in an OS Command, as it allows for command injection through improper handling of user-supplied paths. The flaw enables attackers to execute arbitrary code with the privileges of the libvirtd daemon, which typically runs with root or high-privilege permissions. This creates a significant attack surface where unauthorized users can leverage the vulnerability to escalate their privileges and potentially gain complete control over the host system.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with a mechanism to execute arbitrary commands on the host system. Since libvirtd typically operates with elevated privileges, successful exploitation allows attackers to run malicious code with root-level permissions, potentially leading to complete system compromise. The vulnerability is particularly dangerous in multi-tenant environments or cloud infrastructure where multiple users share the same host system, as it can be exploited by low-privilege users to gain unauthorized access to other virtual machines or system resources. Attackers can leverage this vulnerability to establish persistent backdoors, exfiltrate sensitive data, or disrupt services within the virtualized environment.
Mitigation strategies for CVE-2019-10167 should focus on immediate patching of affected libvirt versions to the secure releases 4.10.1 and 5.4.1 respectively. Organizations should also implement strict access controls and network segmentation to limit exposure of libvirt APIs to untrusted users. Additional defensive measures include disabling unnecessary libvirt APIs, implementing proper input validation for all user-supplied parameters, and monitoring for suspicious execution patterns of binaries. From an ATT&CK framework perspective, this vulnerability maps to T1068 Privilege Escalation and T1059 Command and Scripting Interpreter, as it enables both privilege escalation and arbitrary code execution. System administrators should also consider implementing runtime protection mechanisms such as mandatory access controls or application whitelisting to prevent execution of unauthorized binaries, particularly those that might be used in exploitation attempts. Regular security audits and vulnerability assessments should be conducted to identify similar insecure parameter handling patterns in other system components.