CVE-2026-64490 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
ALSA: virtio: Validate control metadata from the device
virtio-snd control handling trusts the device-provided control type and value count returned by the device.
That metadata is then used directly to index g_v2a_type_map[] in
virtsnd_kctl_info(), and to size loops and memcpy() operations in virtsnd_kctl_get() and virtsnd_kctl_put() against fixed-size virtio_snd_ctl_value and snd_ctl_elem_value arrays.
A buggy or malicious device can therefore trigger out-of-bounds access by advertising an invalid control type or an oversized value count.
Validate control type and count once in virtsnd_kctl_parse_cfg(), before querying enumerated items or exposing the control to ALSA.
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Analysis
by VulDB Data Team • 07/26/2026
The vulnerability identified in the Linux kernel relates to a critical flaw in the ALSA virtio sound subsystem that exposes the system to potential out-of-bounds memory access exploits. This issue affects the virtio-snd driver which handles audio control operations through the virtio transport mechanism, creating a pathway for malicious or faulty hardware devices to compromise system stability and security. The vulnerability stems from inadequate validation of metadata provided by virtio sound devices during control operation handling.
The technical flaw manifests in the improper trust placed in device-provided control metadata within the virtio-snd subsystem. When processing audio control operations, the driver directly utilizes control type information and value counts returned by the device without adequate validation against predefined bounds. This unvalidated metadata is subsequently used to index the g_v2a_type_map[] array in the virtsnd_kctl_info() function, while also determining loop boundaries and memory copy operations in both virtsnd_kctl_get() and virtsnd_kctl_put() functions. The fixed-size arrays virtio_snd_ctl_value and snd_ctl_elem_value serve as targets for these memory operations, making them vulnerable to buffer overflow conditions when maliciously crafted metadata is provided.
The operational impact of this vulnerability extends beyond simple system instability to potentially enable privilege escalation and arbitrary code execution within the kernel space. An attacker controlling a malicious or compromised virtio sound device can exploit this flaw by advertising invalid control types or oversized value counts that exceed the bounds of allocated memory structures. This allows for out-of-bounds memory access patterns that could overwrite critical kernel data structures, potentially leading to denial of service conditions or more severe security breaches depending on the specific memory locations affected. The vulnerability represents a classic buffer overflow condition that violates fundamental security principles of input validation and bounds checking.
This vulnerability aligns with CWE-129, which addresses improper validation of array indices, and CWE-787, covering out-of-bounds write operations. From an adversarial perspective, the flaw maps to ATT&CK technique T1068, specifically "Exploitation for Privilege Escalation" through kernel-level vulnerabilities, and T1499, representing "Endpoint Denial of Service" through resource exhaustion or memory corruption attacks. The mitigation strategy requires implementing proper validation of control metadata at the earliest possible point in the processing pipeline, specifically within the virtsnd_kctl_parse_cfg() function before any enumerated items are queried or controls are exposed to the ALSA subsystem. This approach ensures that all subsequent operations can safely assume valid metadata without requiring additional bounds checking throughout the control handling functions, thereby preventing the out-of-bounds access conditions that could otherwise occur during memory operations.