CVE-2020-25650 in spice-vdagentd
Summary
by MITRE • 11/26/2020
A flaw was found in the way the spice-vdagentd daemon handled file transfers from the host system to the virtual machine. Any unprivileged local guest user with access to the UNIX domain socket path `/run/spice-vdagentd/spice-vdagent-sock` could use this flaw to perform a memory denial of service for spice-vdagentd or even other processes in the VM system. The highest threat from this vulnerability is to system availability. This flaw affects spice-vdagent versions 0.20 and previous versions.
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Analysis
by VulDB Data Team • 05/16/2025
The vulnerability identified as CVE-2020-25650 resides within the spice-vdagentd daemon, a critical component of the SPICE (Simple Protocol for Independent Computing Environments) virtualization framework that facilitates communication between host and guest virtual machines. This daemon manages various virtualized desktop functionalities including clipboard sharing, file transfers, and display protocol handling. The flaw manifests in the daemon's improper handling of file transfer operations originating from the host system, creating a significant security risk within virtualized environments where guest operating systems must trust host communications for proper functionality.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within the spice-vdagentd process when processing file transfer requests through the UNIX domain socket interface. Specifically, unprivileged local users who possess access to the designated socket path at `/run/spice-vdagentd/spice-vdagent-sock` can exploit a memory handling flaw to trigger a denial of service condition. This occurs because the daemon fails to properly validate the size and structure of incoming file transfer data, allowing maliciously crafted transfer requests to cause memory corruption or excessive memory consumption that ultimately leads to process termination or system instability.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire virtualized environment's availability. When exploited, the memory denial of service can affect not only the spice-vdagentd daemon itself but also other critical processes running within the virtual machine, creating cascading failures that may render the guest operating system unstable or completely non-functional. This threat level is particularly concerning in enterprise virtualization environments where multiple virtual machines share host resources and the failure of one service can impact overall system availability and user productivity. The vulnerability affects all versions of spice-vdagent through version 0.20, representing a substantial attack surface across numerous virtualization deployments.
This vulnerability aligns with CWE-121, which describes "Stack-based Buffer Overflow", and CWE-122, which covers "Heap-based Buffer Overflow", as the memory handling flaws in the daemon's file transfer processing likely involve improper buffer management during data reception. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1499.004, "Endpoint Denial of Service", and potentially T1059.001, "Command and Scripting Interpreter", as attackers could leverage this flaw to execute denial of service attacks against virtualized systems. Organizations should implement immediate mitigations including restricting access to the UNIX domain socket path through proper file system permissions, updating to patched versions of spice-vdagent, and monitoring for unauthorized access attempts to the socket interface to prevent exploitation of this availability threat.