CVE-2026-46048
Analyzed Analyzed - Analysis Complete
USB Device Reference Leak in Linux Kernel ALSA caiaq Driver

Publication date: 2026-05-27

Last updated on: 2026-06-16

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: fix usb_dev refcount leak on probe failure create_card() takes a reference on the USB device with usb_get_dev() and stores the matching usb_put_dev() in card_free(), which is installed as the snd_card's ->private_free destructor. However, ->private_free is only assigned near the end of init_card(), after several failure points (usb_set_interface(), EP type checks, usb_submit_urb(), the EP1_CMD_GET_DEVICE_INFO exchange, and its timeout). When any of those fail, init_card() returns an error to snd_probe(), which calls snd_card_free(card). Because ->private_free is still NULL, card_free() never runs, the usb_get_dev() reference is not dropped, and the struct usb_device leaks along with its descriptor allocations and device_private. syzbot reproduces this with a malformed UAC3 device whose only valid altsetting is 0; init_card()'s usb_set_interface(usb_dev, 0, 1) call fails with -EIO and triggers the leak. Move the ->private_free assignment into create_card(), immediately after usb_get_dev(), so that every error path reaching snd_card_free() balances the reference. card_free()'s callees (snd_usb_caiaq_input_free, free_urbs, kfree) already tolerate the partially-initialized state because the chip private area is zero-initialized by snd_card_new().
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Meta Information
Published
2026-05-27
Last Modified
2026-06-16
Generated
2026-06-16
AI Q&A
2026-05-27
EPSS Evaluated
2026-06-15
NVD
CVE-2026-46048
EUVD
EUVD-2026-32430
Affected Vendors & Products
Showing 5 associated CPEs
Vendor Product Version / Range
linux linux_kernel 7.1
linux linux_kernel From 6.12.84 (inc) to 6.12.86 (exc)
linux linux_kernel From 6.18.25 (inc) to 6.18.27 (exc)
linux linux_kernel From 6.6.136 (inc) to 6.6.140 (exc)
linux linux_kernel From 7.0.2 (inc) to 7.0.4 (exc)
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Exploitability
CWE
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability is a reference count leak in the Linux kernel's ALSA caiaq USB driver. When the driver tries to initialize a USB audio device, it takes a reference on the USB device using usb_get_dev(). However, if certain initialization steps fail early, the cleanup function that would normally release this reference is not set, causing the reference to never be dropped.

As a result, the USB device structure and its associated resources leak memory. This happens because the private_free destructor is assigned too late in the initialization process, so if an error occurs before that assignment, the cleanup code does not run.

The fix moves the assignment of the private_free destructor earlier, immediately after the usb_get_dev() call, ensuring that any failure path properly releases the reference and prevents the leak.

Impact Analysis

This vulnerability can lead to a memory leak in the Linux kernel when using the ALSA caiaq USB audio driver. Specifically, if the driver encounters certain errors during device initialization, it will leak references to USB device structures and their associated memory.

Over time, this leak can cause increased memory usage, potentially leading to degraded system performance or instability, especially on systems that frequently connect and disconnect affected USB audio devices.

Mitigation Strategies

This vulnerability is related to a reference count leak in the ALSA caiaq USB driver in the Linux kernel, which occurs on probe failure due to improper handling of usb_dev references.

To mitigate this vulnerability, update your Linux kernel to a version that includes the fix where the private_free destructor is assigned immediately after usb_get_dev() in create_card(), ensuring proper cleanup on all error paths.

Avoid using malformed UAC3 USB devices that trigger the usb_set_interface() failure, as this is the condition that reproduces the leak.

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