CVE-2024-25744 – This vulnerability in the Linux kernel allows a... (How to Fix)

Q: What is the severity of CVE-2024-25744?

CVE-2024-25744 has a CVSS score of 8.8 (HIGH). This vulnerability in the Linux kernel allows an untrusted virtual machine monitor (VMM/hypervisor) to trigger int80 syscall handling at arbitrary times, potentially bypassing security boundaries in Trusted Execution Environments (TEEs) like Intel TDX and AMD SEV. It affects systems running vulnerable Linux kernel versions with TEE features enabled. The vulnerability could allow a malicious hypervisor to compromise guest VM security.

📋 TL;DR

This vulnerability in the Linux kernel allows an untrusted virtual machine monitor (VMM/hypervisor) to trigger int80 syscall handling at arbitrary times, potentially bypassing security boundaries in Trusted Execution Environments (TEEs) like Intel TDX and AMD SEV. It affects systems running vulnerable Linux kernel versions with TEE features enabled. The vulnerability could allow a malicious hypervisor to compromise guest VM security.

💻 Affected Systems

Products:

Linux kernel

Versions: All versions before 6.6.7

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires TEE features (Intel TDX or AMD SEV) to be enabled and used. Cloud environments with untrusted hypervisors are particularly vulnerable.

📦 What is this software?

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

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⚠️ Risk & Real-World Impact

🔴

Worst Case

A malicious hypervisor could execute arbitrary code in guest VMs, bypass TEE protections, access encrypted memory, and potentially achieve full VM escape to compromise the host system.

🟠

Likely Case

A compromised or malicious VMM could bypass TEE security guarantees, potentially accessing sensitive data within protected guest VMs or disrupting their normal operation.

🟢

If Mitigated

With proper hypervisor security controls and isolation, the attack surface is reduced, but the fundamental vulnerability in guest kernel protection remains.

🌐 Internet-Facing: LOW - This requires hypervisor-level access, which is typically not directly internet-facing.

🏢 Internal Only: HIGH - Cloud providers, virtualization hosts, and container platforms with untrusted VMMs are at significant risk.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires hypervisor-level access and knowledge of TEE internals. No public exploits have been reported as of the advisory date.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel 6.6.7 and later

Vendor Advisory: https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.6.7

Restart Required: Yes

Instructions:

1. Update Linux kernel to version 6.6.7 or later. 2. For distributions: Use package manager (apt/yum/dnf) to install latest kernel updates. 3. Reboot system to load new kernel. 4. Verify kernel version with 'uname -r'.

🔧 Temporary Workarounds

Disable TEE features

linux

Disable Intel TDX or AMD SEV features if not required, reducing attack surface.

For Intel TDX: Add 'tdx=off' to kernel boot parameters
For AMD SEV: Add 'mem_encrypt=off' to kernel boot parameters

🧯 If You Can't Patch

Isolate virtualization hosts from untrusted networks and implement strict hypervisor access controls.
Monitor hypervisor activity for unusual behavior and implement additional VM isolation layers.

🔍 How to Verify

Check if Vulnerable:

Check kernel version with 'uname -r'. If version is earlier than 6.6.7 and TEE features are enabled, system is vulnerable.

Check Version:

uname -r

Verify Fix Applied:

After patching, verify kernel version is 6.6.7 or later with 'uname -r'. Check that system boots successfully with TEE features enabled.

📡 Detection & Monitoring

Log Indicators:

Kernel logs showing unexpected int80 syscall handling
Hypervisor logs showing unusual VM behavior
TEE-related error messages

Network Indicators:

Unusual hypervisor management traffic
Anomalous VM-to-hypervisor communication patterns

SIEM Query:

source="kernel" AND ("int80" OR "tdx" OR "sev") AND ("unexpected" OR "error" OR "violation")

📊 Metadata

CVE ID: CVE-2024-25744

CVSS v3 Score: 8.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CWE: CWE-693

Published: February 12, 2024

Last Updated: May 7, 2025

🔗 References

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