Kernel crash via unchecked clock-source lookup
Published Apr 10, 2024 · Updated Jun 19, 2026
NULL pointer dereference in the ALSA USB-audio clock path in Linux allows local users to crash the kernel through a malformed device. snd_usb_set_sample_rate_v2v3 dereferences the cs_desc result from snd_usb_find_clock_source without checking whether a clock-source descriptor was found. A local low-privileged user must cause ALSA to process a USB Audio Class 2 or 3 device with a missing clock-source descriptor; exploitation crashes the kernel without reported data disclosure or modification.
Summary
What happened
NULL pointer dereference in the ALSA USB-audio clock path in Linux allows local users to crash the kernel through a malformed device. snd_usb_set_sample_rate_v2v3 dereferences the cs_desc result from snd_usb_find_clock_source without checking whether a clock-source descriptor was found. A local low-privileged user must cause ALSA to process a USB Audio Class 2 or 3 device with a missing clock-source descriptor; exploitation crashes the kernel without reported data disclosure or modification.
The record
- CVE
- CVE-2021-47211
- Published
- Apr 10, 2024
- Updated
- Jun 19, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-476
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 10, 2024CVE publishedPublication date reported by the CVE source.
- Jun 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=1dc669fed61a4ec4270a89e5fb3535802cc45668 <3455984b16eeb6914caf8b59498ef24fcc1f0a78
- Affected versionversion=1dc669fed61a4ec4270a89e5fb3535802cc45668 <58fa50de595f152900594c28ec9915c169643739
- Affected versionversion=1dc669fed61a4ec4270a89e5fb3535802cc45668 <b97053df0f04747c3c1e021ecbe99db675342954
- Affected versionversion=3.10
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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