CVE-2024-0340 Overview
A memory information disclosure vulnerability exists in the Linux kernel's vhost driver, specifically in the vhost_new_msg() function located in drivers/vhost/vhost.c. The vulnerability stems from improper memory initialization when passing messages between virtual guests and the host operating system. This flaw allows local privileged users to potentially read sensitive kernel memory contents by reading from the /dev/vhost-net device file.
Critical Impact
Local privileged attackers can exploit this uninitialized memory vulnerability to leak sensitive kernel memory contents, potentially exposing cryptographic keys, credentials, or other security-critical data stored in kernel memory.
Affected Products
- Linux Kernel (versions prior to the fix)
- Linux Kernel 6.4-rc1 through 6.4-rc5
- Systems utilizing vhost-net virtualization
Discovery Timeline
- January 9, 2024 - CVE-2024-0340 published to NVD
- May 14, 2025 - Last updated in NVD database
Technical Details for CVE-2024-0340
Vulnerability Analysis
This vulnerability is classified as an information disclosure issue (CWE-200) caused by uninitialized memory use. The vhost_new_msg() function in the vhost driver fails to properly initialize memory structures before they are used to pass messages between virtual machine guests and the host operating system. When a privileged local user reads from the /dev/vhost-net device file, portions of kernel memory that were not properly zeroed may be exposed, leading to information leakage.
The vhost subsystem is a critical component in Linux kernel virtualization, providing high-performance backend implementations for virtio devices. The vhost-net driver specifically handles network I/O for virtual machines, making this vulnerability particularly relevant for virtualization environments and container platforms.
Root Cause
The root cause is improper memory initialization in the vhost_new_msg() function. When allocating or reusing memory structures for inter-process communication between the guest and host, the function does not ensure that all memory regions are properly zeroed or initialized before use. This leaves residual data from previous kernel operations accessible to the reader.
Attack Vector
The attack requires local access with elevated privileges. An attacker with access to read from /dev/vhost-net can exploit this vulnerability by:
- Opening the /dev/vhost-net device file with appropriate permissions
- Performing read operations on the device
- Analyzing the returned data for uninitialized memory regions containing kernel memory contents
The vulnerability mechanism involves the improper initialization of message structures in the vhost driver. When vhost_new_msg() prepares messages for communication between the host and guest systems, it fails to zero out memory buffers before populating them with new data. This allows kernel memory contents from previous operations to leak through read operations on the /dev/vhost-net device. For detailed technical analysis, refer to the Kernel Mailing List Discussion.
Detection Methods for CVE-2024-0340
Indicators of Compromise
- Unusual read activity on /dev/vhost-net device file
- Processes with elevated privileges repeatedly accessing vhost device files
- Anomalous memory access patterns in virtualization-related kernel modules
- Unexpected data exfiltration attempts from hosts running virtual machines
Detection Strategies
- Monitor file access to /dev/vhost-net using auditd or similar kernel auditing tools
- Implement syscall monitoring for read operations targeting vhost device files
- Deploy endpoint detection solutions capable of identifying suspicious kernel memory access patterns
- Review system logs for processes with unusual vhost device interactions
Monitoring Recommendations
- Enable kernel auditing for vhost-related device file access with rules targeting /dev/vhost-net
- Configure SIEM alerts for repeated read operations on virtualization device files from non-standard processes
- Monitor process behavior for data exfiltration patterns following vhost device access
- Implement file integrity monitoring on kernel modules related to vhost subsystem
How to Mitigate CVE-2024-0340
Immediate Actions Required
- Apply the latest kernel patches from your Linux distribution vendor
- Review and restrict access permissions to /dev/vhost-net device files
- Audit systems for unauthorized privileged access to virtualization components
- Consider isolating affected virtualization hosts until patches are applied
Patch Information
Security patches addressing this vulnerability are available from multiple vendors. Red Hat has released patches in RHSA-2024:3618, RHSA-2024:3627, and RHSA-2024:9315. Debian has also provided updates as documented in the Debian LTS Announcements. Consult the Red Hat Bugzilla Report #2257406 for additional tracking information.
Workarounds
- Restrict access to /dev/vhost-net to only essential processes and users
- Implement strict access control policies using SELinux or AppArmor to limit vhost device access
- Monitor and audit all privileged access to virtualization subsystems
- Consider disabling vhost-net if not required for your virtualization workloads
# Restrict access to vhost-net device
chmod 600 /dev/vhost-net
chown root:root /dev/vhost-net
# Add audit rule for vhost device access monitoring
auditctl -w /dev/vhost-net -p r -k vhost_access
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
