CVE-2021-47352 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
virtio-net: Add validation for used length
This adds validation for used length (might come from an untrusted device) to avoid data corruption or loss.
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Analysis
by VulDB Data Team • 08/07/2026
The vulnerability identified as CVE-2021-47352 resides within the Linux kernel's virtio-net driver implementation, specifically addressing a critical validation gap in how the system processes used length parameters. This flaw represents a significant security concern as it directly impacts the virtualized network interface functionality that millions of systems rely upon for network communication. The vulnerability manifests when the virtio-net subsystem receives a used length value that originates from a potentially untrusted virtual device, creating an avenue for malicious actors to manipulate network data processing.
The technical root cause of this vulnerability lies in the absence of proper input validation for the used length parameter within the virtio-net driver's processing logic. When virtual devices communicate with the host system through virtio interfaces, they transmit metadata including used length indicators that specify how much data has been processed or consumed. Without adequate validation of these values, an attacker controlling a malicious virtual device could craft invalid used length values that exceed buffer boundaries or manipulate data structures in ways that lead to memory corruption. This vulnerability directly maps to CWE-129 Input Validation and CWE-787 Out-of-bounds Write, as it allows for improper bounds checking and potential memory corruption scenarios.
The operational impact of this vulnerability extends across various virtualized environments where Linux systems utilize virtio network drivers, including cloud computing platforms, containerized environments, and virtual machine deployments. Attackers could exploit this weakness to cause data corruption, information disclosure, or potentially achieve privilege escalation within the virtualized environment. The vulnerability is particularly dangerous in multi-tenant cloud environments where one malicious tenant could potentially impact the network operations of other tenants through crafted network packets that manipulate the used length values. This aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as the vulnerability could enable attackers to manipulate system resources and potentially gain elevated privileges.
The mitigation strategy for CVE-2021-47352 involves implementing proper validation checks for the used length parameter before it is processed by the virtio-net driver. The fix ensures that the driver validates the received used length values against expected bounds and rejects any values that exceed reasonable parameters or fall outside the valid range for the network buffer being processed. This validation prevents malicious or malformed used length values from causing data corruption or memory access violations. System administrators should ensure their Linux kernels are updated to versions containing the patched virtio-net driver implementation, which typically includes bounds checking for the used length parameter and proper error handling for invalid values. Organizations utilizing virtualized environments should prioritize patching their kernel versions and monitor for any potential exploitation attempts targeting this vulnerability in their network infrastructure.