CVE-2026-98741

Received Received - Intake

Buffer Overflow in Linux Kernel ALSA UA-101 Driver

Publication date: 2026-10-18

Last updated on: 2026-10-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: ua101: reject mismatched capture/playback packet sizes detect_usb_format() cross-checks bSubframeSize, bBitResolution and tSamFreq between the capture and playback interfaces, but never relates the two endpoints' wMaxPacketSize and bNrChannels. Each playback URB gets a buffer of ua->playback.max_packet_bytes, while the number of bytes written into it is derived from the capture stream: capture_urb_complete() computes frames from the received capture packet and capture.frame_bytes, and start_usb_playback() and playback_work() multiply that by playback.frame_bytes. A device declaring a large capture wMaxPacketSize with few capture channels and a small playback wMaxPacketSize with many playback channels therefore memset()s and memcpy()s past the end of the playback buffer, in open() of the PCM node the driver registers during probe. usb_submit_urb() rejects the over-long iso_frame_desc[0].length with -EMSGSIZE, but only after the write. Reject such descriptors at probe time. Genuine UA-101/UA-1000 hardware declares proportional packet sizes and is unaffected. BUG: KASAN: slab-out-of-bounds in start_usb_playback (sound/usb/misc/ua101.c:586) Write of size 2048 at addr ffff8881098f3c00 by task exploit/5021 Call Trace: __asan_memset (mm/kasan/shadow.c:84) start_usb_playback (sound/usb/misc/ua101.c:586) playback_pcm_open (sound/usb/misc/ua101.c:679) snd_pcm_open_substream (sound/core/pcm_native.c:2829) snd_pcm_open (sound/core/pcm_native.c:2865 sound/core/pcm_native.c:2932) snd_pcm_playback_open (sound/core/pcm_native.c:2891) snd_open (sound/core/sound.c:166) chrdev_open (fs/char_dev.c:411) do_dentry_open (fs/open.c:996) vfs_open (fs/open.c:1101) path_openat (fs/namei.c:4837 fs/namei.c:5000) do_file_open (fs/namei.c:5029) do_sys_openat2 (fs/open.c:1417) __x64_sys_openat (fs/open.c:1423 fs/open.c:1439 fs/open.c:1434) do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address belongs to the object at ffff8881098f3c00 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 0 bytes inside of allocated 168-byte region [ffff8881098f3c00, ffff8881098f3ca8)

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-18

Last Modified

2026-10-19

Generated

2026-10-19

AI Q&A

2026-10-18

EPSS Evaluated

N/A

NVD

CVE-2026-98741

EUVD

EUVD-2026-103826

Affected Vendors & Products

Vendor	Product	Version / Range
Linux	Linux	63978ab3e3e963db28093b53bb4598f2702e1ad7
Linux	Linux	63978ab3e3e963db28093b53bb4598f2702e1ad7
Linux	Linux	63978ab3e3e963db28093b53bb4598f2702e1ad7
Linux	Linux	63978ab3e3e963db28093b53bb4598f2702e1ad7
Linux	Linux	2.6.34

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a buffer overflow in the ALSA ua101 driver. It occurs when mismatched capture and playback packet sizes are detected but not properly validated. The driver fails to check wMaxPacketSize and bNrChannels between endpoints, leading to memory corruption when writing data past the allocated playback buffer during PCM node open operations.

Detection Guidance

This vulnerability is specific to the Linux kernel's ALSA ua101 driver and requires examining kernel logs for slab-out-of-bounds errors related to the ua101 module. Check for KASAN reports in dmesg or system logs indicating memory corruption in sound/usb/misc/ua101.c.

Impact Analysis

An attacker could exploit this to cause a denial of service or potentially execute arbitrary code with kernel privileges. The vulnerability allows memory corruption via buffer overflow, which could crash the system or enable privilege escalation if exploited through a malicious USB device.

Compliance Impact

This vulnerability is a kernel memory corruption issue in the Linux ALSA USB audio driver (ua101) that could lead to buffer overflows during audio device initialization. It does not directly relate to data privacy, access control, or audit logging requirements in standards like GDPR or HIPAA. The impact is limited to potential system instability or crashes on affected systems.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for CVE-2026-98741. Avoid using untrusted USB audio devices until the system is updated. Monitor kernel logs for any signs of exploitation attempts targeting the ua101 driver.

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