CVE-2024-2494 in libvirt
Summary
by MITRE • 03/21/2024
A flaw was found in the RPC library APIs of libvirt. The RPC server deserialization code allocates memory for arrays before the non-negative length check is performed by the C API entry points. Passing a negative length to the g_new0 function results in a crash due to the negative length being treated as a huge positive number. This flaw allows a local, unprivileged user to perform a denial of service attack by causing the libvirt daemon to crash.
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Analysis
by VulDB Data Team • 08/02/2025
The vulnerability identified as CVE-2024-2494 resides within the remote procedure call library APIs of libvirt, a critical virtualization management library that provides APIs for managing virtual machines and hypervisors. This flaw represents a classic buffer over-read condition that manifests during the deserialization process of RPC server communications. The issue specifically affects how the RPC server handles array memory allocation, creating a dangerous race condition between memory allocation and input validation. When the C API entry points process incoming data, they perform a non-negative length check after memory allocation has already occurred, leaving a window where malformed input can cause catastrophic system behavior.
The technical exploitation of this vulnerability occurs through the g_new0 function, which serves as a memory allocation utility within the libvirt codebase. When a negative length value is passed to this function, the underlying memory allocation mechanism treats the negative value as an enormous positive number due to the unsigned nature of memory allocation parameters. This misinterpretation results in massive memory allocation requests that exceed system limits, ultimately causing the libvirt daemon to crash and terminate unexpectedly. The flaw operates at the intersection of memory management and input validation, creating a scenario where improper bounds checking leads to resource exhaustion and system instability.
The operational impact of CVE-2024-2494 extends beyond simple denial of service, as it represents a fundamental weakness in the libvirt daemon's security architecture. This vulnerability allows any local, unprivileged user to execute a denial of service attack against the virtualization infrastructure, potentially disrupting critical virtual machine operations and hypervisor management services. The attack vector is particularly concerning because it requires no elevated privileges, making it accessible to any user with basic system access. From an attacker's perspective, this vulnerability aligns with the ATT&CK technique T1499.004 (Network Denial of Service) and represents a low-effort, high-impact method for compromising system availability. The vulnerability also relates to CWE-129, which describes improper validation of length parameters, and CWE-704, which covers incorrect type conversion or cast operations.
Mitigation strategies for CVE-2024-2494 should focus on implementing immediate code-level fixes that enforce proper input validation before memory allocation occurs. The most effective approach involves modifying the RPC server deserialization code to validate array length parameters immediately upon entry to C API functions, ensuring that negative values are rejected before any memory allocation takes place. System administrators should also consider implementing monitoring solutions to detect unusual patterns of libvirt daemon crashes and establish automated restart procedures for critical virtualization services. Additionally, regular updates to the libvirt library should be prioritized, as this vulnerability affects the core functionality of virtualization management systems and represents a security risk that could be exploited in broader attack scenarios. The vulnerability demonstrates the importance of proper input sanitization and memory management practices, aligning with security best practices outlined in the NIST SP 800-160 standard for secure software development lifecycle methodologies.