CVE-2026-64489 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
ALSA: ymfpci: check snd_ctl_new1() return value
snd_ctl_new1() can return NULL when memory allocation fails. snd_ymfpci_create_spdif_controls() does not check the return value before dereferencing kctl->id.device, which can lead to a NULL pointer dereference.
Add NULL checks after snd_ctl_new1() calls and return -ENOMEM if any fails.
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Analysis
by VulDB Data Team • 07/25/2026
The vulnerability resides within the Linux kernel's Advanced Linux Sound Architecture subsystem, specifically in the ymfpci driver that handles Yamaha YMF724 sound chips. This issue represents a classic null pointer dereference flaw that can lead to system instability and potential privilege escalation opportunities. The problem manifests when the snd_ctl_new1() function fails during memory allocation, returning a NULL pointer instead of a valid control structure. The ymfpci driver's snd_ymfpci_create_spdif_controls() function does not properly validate this return value before proceeding with operations that assume the pointer is valid.
The technical implementation flaw stems from inadequate error handling in the driver's control creation routine where memory allocation failures are not appropriately managed. When snd_ctl_new1() fails to allocate memory for a sound control structure, it returns NULL, but the subsequent code directly dereferences this potentially null pointer by accessing kctl->id.device without prior validation. This pattern violates fundamental defensive programming practices and creates a clear path for system crashes or more severe exploitation scenarios.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the stability of audio subsystems in Linux environments. Attackers could exploit this weakness by triggering memory allocation failures through specific audio configurations or by exhausting system resources, causing the kernel to crash when attempting to create sound controls. The vulnerability affects systems running Linux kernels with the ymfpci driver enabled and could be particularly problematic in server environments where audio functionality is required but not properly secured.
From a cybersecurity perspective, this vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a potential entry point for privilege escalation attacks. The issue follows ATT&CK technique T1068 by creating opportunities to exploit kernel-level memory management flaws. The recommended mitigation involves implementing proper error checking after each snd_ctl_new1() call, returning -ENOMEM to indicate allocation failure, and ensuring all subsequent pointer operations are protected by null checks. This approach aligns with the principle of least privilege and defensive programming practices that prevent cascading failures in kernel space operations. The fix requires minimal code changes but significantly improves the driver's robustness against memory allocation failures and enhances overall system stability.
The vulnerability demonstrates how seemingly minor oversight in error handling can create significant security implications within kernel drivers, highlighting the importance of comprehensive testing for allocation failure scenarios and adherence to established kernel development practices that emphasize robustness and proper resource management.