CVE-2024-3446 in QEMU
Summary
by MITRE • 04/09/2024
A double free vulnerability was found in QEMU virtio devices (virtio-gpu, virtio-serial-bus, virtio-crypto), where the mem_reentrancy_guard flag insufficiently protects against DMA reentrancy issues. This issue could allow a malicious privileged guest to crash the QEMU process on the host, resulting in a denial of service or allow arbitrary code execution within the context of the QEMU process on the host.
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Analysis
by VulDB Data Team • 09/14/2025
The double free vulnerability identified as CVE-2024-3446 represents a critical security flaw within QEMU's virtualization infrastructure that specifically targets virtio device implementations including virtio-gpu, virtio-serial-bus, and virtio-crypto components. This vulnerability stems from inadequate protection mechanisms around memory reentrancy guard flags, creating a scenario where malicious privileged guests can exploit the system's memory management to trigger unintended behavior. The flaw manifests when DMA (Direct Memory Access) operations attempt to reenter memory regions that have already been freed, leading to potential memory corruption and system instability. The vulnerability operates at the intersection of virtualization security and memory management, where the protective mechanisms designed to prevent DMA reentrancy prove insufficient against sophisticated attack vectors.
The technical implementation of this vulnerability exploits the mem_reentrancy_guard flag mechanism that is intended to prevent recursive DMA operations from corrupting memory structures. However, the current implementation fails to properly enforce memory access restrictions when multiple DMA operations occur in rapid succession or when the guest operating system manipulates memory pointers in unexpected ways. This allows an attacker to manipulate the memory state such that a free operation occurs twice on the same memory block, leading to heap corruption and potential code execution. The vulnerability demonstrates characteristics consistent with CWE-415 Double Free, where the same memory location is freed twice, and the exploitation can occur through guest-level privileges that have access to virtualized hardware interfaces.
The operational impact of CVE-2024-3446 extends beyond simple denial of service scenarios to potentially enable arbitrary code execution within the QEMU process context, representing a severe privilege escalation risk. When exploited, the vulnerability can cause the QEMU process to crash or become unstable, resulting in complete system denial of service for all virtual machines hosted on that system. More critically, the memory corruption resulting from the double free operation can be leveraged to execute arbitrary code with the privileges of the QEMU process, which typically runs with elevated permissions on the host system. This creates a significant attack surface where malicious guests can potentially compromise the entire host environment and potentially escalate to full system compromise. The vulnerability affects virtualization environments that utilize the affected virtio devices, making it particularly dangerous in cloud computing and server virtualization scenarios.
Mitigation strategies for CVE-2024-3446 require immediate patch application from QEMU maintainers, as the vulnerability cannot be effectively addressed through configuration changes alone. Organizations should implement comprehensive monitoring of virtualization hosts for signs of exploitation attempts, particularly focusing on unusual memory access patterns and DMA operations. The mitigation approach should include immediate deployment of updated QEMU versions that properly address the mem_reentrancy_guard flag implementation and ensure adequate protection against DMA reentrancy scenarios. System administrators should also consider implementing additional security controls such as memory protection mechanisms, process isolation, and privilege restrictions on virtual machine guests. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as it allows for code execution and privilege escalation within the virtualization environment. Regular security assessments of virtualization infrastructure and monitoring for anomalous behavior patterns are essential to detect potential exploitation attempts before they can be successfully executed.