Kernel memory corruption via UBI ioctl race
Published Feb 26, 2025 · Updated May 23, 2026
Use-after-free in the Linux kernel UBI subsystem allows local users to corrupt kernel memory by racing UBI volume-management ioctls. The ctrl_cdev_ioctl attach path holds ubi_devices_mutex while ubi_cdev_ioctl uses ubi->device_mutex, allowing uif_init or uif_close to overlap volume creation and removal and free device structures twice. Exploitation requires local low-privileged access and concurrent attach, create, or remove operations; successful triggering compromises kernel confidentiality, integrity, and availability.
Summary
What happened
Use-after-free in the Linux kernel UBI subsystem allows local users to corrupt kernel memory by racing UBI volume-management ioctls. The ctrl_cdev_ioctl attach path holds ubi_devices_mutex while ubi_cdev_ioctl uses ubi->device_mutex, allowing uif_init or uif_close to overlap volume creation and removal and free device structures twice. Exploitation requires local low-privileged access and concurrent attach, create, or remove operations; successful triggering compromises kernel confidentiality, integrity, and availability.
The record
- CVE
- CVE-2021-47634
- Published
- Feb 26, 2025
- Updated
- May 23, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-416, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 26, 2025CVE publishedPublication date reported by the CVE source.
- May 23, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=016820bde3f0895d09fcad370415085ba0d1bd4a
- Affected versionversion=12f567db822241090b90c5645ea9146f6cf8fa42
- Affected versionversion=3.10.103 <3.11
- Affected versionversion=3.12.63 <3.13
- Affected versionversion=3.14.77 <3.15
- Affected versionversion=3.16.39 <3.17
- Affected versionversion=3.18.40 <3.19
- Affected versionversion=31b0fca8ab9b9786fe6e5027c4a8587b47db5abf
- Affected versionversion=3.2.84 <3.3
- Affected versionversion=4056337b1e81a1b137aa562133dc5430cd2fd19e
- Affected versionversion=4.1.31 <4.2
- Affected versionversion=4.4.19 <4.5
- Affected versionversion=4.7.2 <4.8
- Affected versionversion=4.8
- Affected versionversion=6117840dec60344167038f9511c3770d4c096eaa
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <1a3f1cf87054833242fcd0218de0481cf855f888
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <3cbf0e392f173ba0ce425968c8374a6aa3e90f2e
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <432b057f8e847ae5a2306515606f8d2defaca178
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <5f9e9c223e48c264241d2f34d0bfc29e5fcb5c1b
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <a8ecee49259f8f78d91ddb329ab2be7e6fd01974
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <c32fe764191b8ae8b128588beb96e3718d9179d8
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <d727fd32cbd1abf3465f607021bc9c746f17b5a8
- Affected versionversion=714fb87e8bc05ff78255afc0dca981e8c5242785 <f149b1bd213820363731aa119e5011ca892a2aac
- Affected versionversion=ae32d1b98ba29408df87c0ed47877ca0f248eae7
- Affected versionversion=bd7d3de27e7e1acce2e276074a498a82e0834663
- Affected versionversion=cdf25333b42fb889f086ef65d0734d0dbdc49f4e
- Affected versionversion=f3db4c640b32485105554e0bfd16bbde585f6fb0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
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Public exploit references
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Technologies
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